the local-maps system was changed

What does this mean?

Also see http://kb.mozillazine.org/Disappearing_mail

On the left side under "inbox" there were several maps. All these maps are disappeared. To these maps we could transport and collect emails

On the left side under "inbox" there were several maps.

I suppose you're talking about folders.

Are 'all folders gone or just the Sent folder?

Did the new account wizard come up?

Under inbox (in dutch; postvak In) there are now just 3 folders; recycle bin (in dutch prullenbak), concepts (in dutch concepten) and send (in dutch verzonden). In the past when I double-clicked on the inbox-folder there were a lot of folders. Now nothing appears when I boubleclick on inbox. When I doubleclick on the send-folder nothing appears. In the past there were a lot of items in it, cause I didn't delete them. Too the concept-folder is emty now

In the past when I double-clicked on the inbox-folder

You don't need to double-click, neither Inbox nor Sent.

on the inbox-folder there were a lot of folders.

At the top right of the Thunderbird window, click the menu button > Options > Account Settings - Server Settings

At the bottom is a field 'Local directory'. Please post the entire contents of that field.

I have made a print screen in a Word-document. This document is being uploaded The name of this Word-document is "local directory". I hope it can transported to you

You cannot attach Word documents to posts here. You can post a screenshot though, but this isn't really what I asked you to do.

Please copy the contents of the 'Local Directory' field and paste it into your reply. Pretty simple.

C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail\pop.ziggo.nl\Inbox.sbd

I hope, this is what you meant ??

I'd have expected the path to be C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail\pop.ziggo.nl\

How did you manage to get Inbox.sbd added at the end?

When you open C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail\pop.ziggo.nl\ in Windows Explorer, what files fo you see in that folder?

Please post a screenshot. https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

In case you haven't done this yet, make sure to create a full backup of your Thunderbird profile. https://support.mozilla.org/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

I hope this screenshot is what you are searching? I made a screenshot of " C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail\pop.ziggo.nl\ " Now after this reply I go make a full backup of my Thunderbird !!!!! It's a pity I didn't n know to do this before !!!

The folders 'Concepten' and ' Verzonden' have a site of 0 Bytes, so there certainly is no mail in it. There is mail in Inbox though.

If there are supposed to be other folders then there is no trace of them underneath that path.

If there's anything useful underneath Inbox.sbd you may want to post another screenshot.

Under the folder "inbox.sbd " are several folders, but I can't look inside this folders, cause I don't know which sort of program I had to choose. Is in the screenshot of inbox.sbd anything that is useful for you ?

You managed to create a nested folder structure. I.e. there is now another folder Inbox.sbd underneath Inbox.sbd

C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail\pop.ziggo.nl\Inbox.sbd\Inbox.sbd

From the timestamp of Inbox, this appears to be the one you're currently using.

Can you post another screenshot with the contents of the nested Inbox.sbd folder?

On this screenshot of

C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail\pop.ziggo.nl\Inbox.sbd\Inbox.sbd

the message "Deze map is leeg" means "This file is empty"

So, nothing there either. I really don't know what happened with your missing folders, and what caused the change in the 'Local directory' field.

One last thing to check. Can you post a screenshot with the contents of the folder C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail?

I made a printscreen of the file; C:\Users\Gebruiker\AppData\Roaming\Thunderbird\Profiles\aemb9tas.default\Mail I also made a printscreen of the underlying folders (Local Folders) and (pop.ziggo.nl) The amount of 7 years emails had to be a file with a very great amount of bites (1 or 2 Gb ??). But I don't see a file with such amount of bites here. This region is the only place Thunderbird saves the emails ?

What other accounts are set up in Thunderbird?

Is any of your accounts set up for Global Inbox?

Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button , then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

Did you mess with the 'Local directory' setting for the pop.ziggo.nl account?

My only account is tienen@nl. and I have only ziggo.nl as my provider. I am sure my account is not set up for Global Inbox My only other emailadres is a gmail.com.-adres. In the past my youngest son has formatted the computer in 2004 and 2010. He saved then the email content.(This content I still have and is not dissappeared) Two days ago I send a email with a Word-screenshot of our searching with you to him. He then phoned me and we installed a program so he could look and take action in my computer. We were busy a several hours. He looked everywhere, but couldn't discover any file, that could contain the lost emails from 2010 to april 2017. In his opinion the lost emails are finilly disappeared and on the question why and how he didn't had any answer.

The following is the Troubleshooting Information you asked for:

 Toepassingsbasics

   Naam: Thunderbird
   Versie: 45.8.0
   Useragent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0
   Profielmap: Map tonen

             (Lokaal station)
   Build-ID van de toepassing: 20170305125302
   Ingeschakelde plug-ins: about:plugins
   Buildconfiguratie: about:buildconfig
   Geheugengebruik: about:memory

 E-mail- en nieuwsaccounts
   account1:
     INCOMING: account1, , (pop3) pop.ziggo.nl:110, plain, passwordCleartext
     OUTGOING: , smtp.ziggo.nl:587, alwaysSTARTTLS, passwordCleartext, true

   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

 Crashrapporten
   http://crash-stats.mozilla.com/report/index/bp-282828ff-97e5-4a74-ae11-d6d362140404 (4-4-2014)

 Extensies
   Lightning, 4.7.8, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Belangrijke aangepaste voorkeuren

   Naam: Waarde

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     browser.cache.disk.filesystem_reported: 1
     browser.cache.disk.smart_size_cached_value: 358400
     browser.cache.disk.smart_size.first_run: false
     browser.cache.disk.smart_size.use_old_max: false
     dom.apps.reset-permissions: true
     extensions.lastAppVersion: 45.8.0
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     font.name.serif.el: Cambria
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     font.size.fixed.el: 14
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     gfx.blacklist.direct2d: 3
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     gfx.crash-guard.glcontext.deviceID: 0x0046
     gfx.crash-guard.glcontext.driverVersion: 8.15.10.2361
     gfx.crash-guard.glcontext.gfx.driver-init.direct3d11-angle: true
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     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-d3d11: false
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-force-warp: false
     gfx.crash-guard.glcontext.gfx.driver-init.webgl-angle-try-d3d11: true
     gfx.crash-guard.status.glcontext: 2
     gfx.direct3d.last_used_feature_level_idx: 1
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 767eab8f-3041-4858-b8f7-6f85d6d8d41
     mailnews.database.global.views.conversation.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     mailnews.database.global.views.global.columns: {"threadCol":{"visible":true,"ordinal":"3"},"flaggedCol":{"visible":true,"ordinal":"5"},"attachmentCol":{"visible":false…
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1493752288
     places.history.expiration.transient_current_max_pages: 101830
     places.history.expiration.transient_optimal_database_size: 162926754
     plugin.importedState: true
     plugins.update.notifyUser: true
     print.print_printer: Canon MP640 series Printer
     print.printer_Canon_MP640_series_Printer.print_bgcolor: false
     print.printer_Canon_MP640_series_Printer.print_bgimages: false
     print.printer_Canon_MP640_series_Printer.print_colorspace:
     print.printer_Canon_MP640_series_Printer.print_command:
     print.printer_Canon_MP640_series_Printer.print_downloadfonts: false
     print.printer_Canon_MP640_series_Printer.print_duplex: 0
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     print.printer_Canon_MP640_series_Printer.print_footercenter:
     print.printer_Canon_MP640_series_Printer.print_footerleft: &PT
     print.printer_Canon_MP640_series_Printer.print_footerright: &D
     print.printer_Canon_MP640_series_Printer.print_headercenter:
     print.printer_Canon_MP640_series_Printer.print_headerleft: &T
     print.printer_Canon_MP640_series_Printer.print_headerright: &U
     print.printer_Canon_MP640_series_Printer.print_in_color: true
     print.printer_Canon_MP640_series_Printer.print_margin_bottom: 0.5
     print.printer_Canon_MP640_series_Printer.print_margin_left: 0.5
     print.printer_Canon_MP640_series_Printer.print_margin_right: 0.5
     print.printer_Canon_MP640_series_Printer.print_margin_top: 0.5
     print.printer_Canon_MP640_series_Printer.print_oddpages: true
     print.printer_Canon_MP640_series_Printer.print_orientation: 0
     print.printer_Canon_MP640_series_Printer.print_page_delay: 50
     print.printer_Canon_MP640_series_Printer.print_pagedelay: 500
     print.printer_Canon_MP640_series_Printer.print_paper_data: 9
     print.printer_Canon_MP640_series_Printer.print_paper_height: 11,00
     print.printer_Canon_MP640_series_Printer.print_paper_name:
     print.printer_Canon_MP640_series_Printer.print_paper_size_type: 0
     print.printer_Canon_MP640_series_Printer.print_paper_size_unit: 1
     print.printer_Canon_MP640_series_Printer.print_paper_width: 8,50
     print.printer_Canon_MP640_series_Printer.print_plex_name:
     print.printer_Canon_MP640_series_Printer.print_resolution: 0
     print.printer_Canon_MP640_series_Printer.print_resolution_name:
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     print.printer_Canon_MP640_series_Printer.print_unwriteable_margin_right: 0
     print.printer_Canon_MP640_series_Printer.print_unwriteable_margin_top: 0

 Grafisch

     Adapterbeschrijving: Intel(R) HD Graphics
     Vendor-ID: 0x8086
     Device-ID: 0x0046
     Adapter-RAM: Unknown
     Adapterstuurprogramma’s: igdumd64 igd10umd64 igdumdx32 igd10umd32
     Stuurprogrammaversie: 8.15.10.2361
     Datum stuurprogramma: 4-10-2011
     Adapterbeschrijving (GPU #2): NVIDIA GeForce GT 325M
     Vendor-ID (GPU #2): 0x10de
     Device-ID (GPU #2): 0x0a35
     Adapter-RAM (GPU #2): 1024
     Adapterstuurprogramma’s (GPU #2): nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
     Stuurprogrammaversie (GPU #2): 9.18.13.697
     Datum stuurprogramma (GPU #2): 10-2-2012
     Direct2D ingeschakeld: Geblokkeerd voor uw grafische stuurprogramma.
     DirectWrite ingeschakeld: false (6.2.9200.17568)
     ClearType-parameters: ClearType-parameters niet gevonden
     WebGL-renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics Direct3D11 vs_4_0 ps_4_0) -- OpenGL ES 2.0 (ANGLE 2.1.0.316930d51ea9)
     GPU-versnelde vensters: 0

     AzureCanvasBackend: skia
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: cairo

 JavaScript

 Incrementele GC: 1

 Toegankelijkheid

   Geactiveerd: 0
   Toegankelijkheid voorkomen: 0

 Bibliotheekversies

     Verwachte minimale versie
     Gebruikte versie

     NSPR
     4.12
     4.12

     NSS
     3.21.3 Basic ECC
     3.21.3 Basic ECC

     NSS Util
     3.21.3
     3.21.3

     NSS SSL
     3.21.3 Basic ECC
     3.21.3 Basic ECC

     NSS S/MIME
     3.21.3 Basic ECC
     3.21.3 Basic ECC

The reason I was asking for other accounts is the middle screenshot of your previous post. There is an substiantial amount of mail (311 MB) in Inbox, some (56MB) in 'Verzonden items', and even a Sent folder with a size of 243 MB. Those are from 2015 though. Typically mail files are created underneath 'Local Folders' when using Global Inbox. I'd expect you do see all these folders also in Thunderbird, so I guess this isn't any of your missing mail?

There are presumably subfolders underneath the .sbd folders, but their contents isn't visible in the screenshot. If none of your missing messages are to be found there, then I'd agree with your son, that they are gone for good.

I sincerely thank you for all your help and patience. it's a pity the emails are disappeared..... but I think I had to accept it. I wish you all the best...