Your screenshot is of the Mail folder, not the profile folder. I suggest clicking help>troubleshootinginformation, scroll down to 'profile folder' and cllck 'open folder' and do a screenshot of that, as that screenshot will show the profile as thunderbird sees it.

Thanks, is this what is needed? I'm afraid I'm not a whizz-kid with computers, just a user and really don't understand what goes on behind the interface so treat me gently!

Puzzling. There is no Imapmail folder. Did you have IMAP accounts? You appear to have many POP accounts. What do you see on the thunderbird startup pane? How did you create the backup? As an aside, the contents of those POP accounts are probably there and can be saved, but the accounts themselves should be visible.

A couple more screenshots if it helps. The emails were exported from Thunderbird as a zip file created by Thunderbird. The new version of Mint was clean installed and the zip file was imported back with these results. I have only emails, no other files. Both the accounts are POP accounts (Gandi & Yahoo). It's possible I can salvage some from Gandi, I don't know. Over the years I've never found an effective way of saving emails, perhaps it's just me. If it can be solved, great, but please don't loose sleep over it.

You have a 'thunderbird import' folder in local folders. could you do a screenshot of that? Worst case, you can salvage the content. you can do that by these steps:

1. install the importexporttools addon if not already done
2. highlight Local Folders, create a folder for each account (e.g., mailgand3, highlight that new folder, rightclick and select the importexport option to import mbox, and then select one of the message folders in the mail.gandi-3 folder, such as inbox (ignore the .msf entries) and repeat the process for other files, such as sent, closeness, draft. Repeat for other accounts. This moves all messages into Local Folders, organized by their accounts.

Full of nothing as are all the folders below! I'll try what you've suggested but I doubt I'll do it until tomorrow. I'll let you know how I get on. Thanks for all your help. Brian.

I noticed you have a Local Folders within Local Folders. Something you may want to try is this

1. unzip the profile on disc, separate from Thunderbird
2. since you now know where the profiles are stored, rename this profile name and copy to the same folder as the current profile.
3. next, start thunderbird and click help>troubleshootinginformation
4. scroll down to 'profile folder' and click 'about:profiles'
5. click 'create profile' button
6. click Next
7. enter short nickname for profile, such as OLDPROFILE
8. click the 'choose' button to locate and select the profile you copied in
9. click finish and activate

If the zipped profile was intact and not corrupted, thunderbird should use it. since this process does not change the profile currently in use, nothing has been lost and you can revert to it.

Thanks for all your help.

I was happy to assist. :)