Sometimes when Thunderbird is updating, an antivirus or firewall intercepts and causes the update to be incomplete, causing Thunderbird to lose pointer to profile. When that happens, it creates a new profile. So, your stuff is likely still there, but in a different profile. You can investigate this by using windows file explorer to review profiles at c:\users\<yourid>\appdata\roaming\thunderbird\profiles or click help>troubleshootinginformation, scroll down to 'profiles' and click 'about:profiles' and see there if you can locate the profile and/or your data.

I unfortunenately I did not succed in finding my profiledata. I found a profile of today called 'parxSud3.default' containing, what I can identify as various settings including 'mail' and a crash file of the assumed date for crashing named 'InstalTime 20231215200246'. Might that file contain the profile? I opened it as a text file showing a number, 1703166386. does that give any meaning? I am sorry to be unable to enclose *.docx or *.txt file with dump of the first two papes of parxSud3.default. Uploading denied when browsing. What do I do?

That folder, parxsud3.default, is the profile. My guess is you found it at c:\users\<yourid>\appdata\roaming\thunderbird\profiles. Were there other profiles there? If this is the only one, you might try tools>import>import from another thunderbird installation to restore that profile.

Thank you for your reply. Do you mean that I should download Thunderbird again, start it again and import? Did you notice that the file found is from today? Greetings Jens

I did not realize that the file was created today; I inferred you found it today. If that is the only profile in the thunderbird\profiles folder, then I suggest you check the Mail folder to see if your POP account is there. If so, it may be possible to recover the messages, and also the addressbook.

Hi, Thank you for your kind help! I have now uninstalled Thundbird and reinstalled, started the program and imported the folder parxsud3.default. During import I recogniced files that might be the files wanted. However, they do not turn up in the program on restarting. There are two empty "local folders" containing: 1) outbox and trash and 2) trash and unsent messages. Should the profile folder from the instalation have been deleted before the import? Greetings Jens

No, the import doesn't merge profiles. It's normal for an installation to have empty trash and empty outbox folders, so I am unclear on what you are asking. I'm glad you're having progress, though.

Hi again, I was unprecise? I understood that when importing the folder parxsud3.default I might have the missing folders/files back. Was that wrong? Is any way to trace missing folders/files. How do I change the settings so that autoupdate will not take place. Is there a better backup than MozBackup?

Jens

NEVER use mozbackup. Even the author has a note on website that it is out of date. If you used mozbackup, that may account for any omissions. The only safe way to backup a profile is to use the operating system's file copy tool. For windows, the steps are - exit thunderbird (this is IMPORTANT. If TB is running, some files are not copied) - in Windows File Explorer, copy c:\users\<yourid>\appdata\roaming\thunderbird to external media - if you need to restore, first install Thunderbird if not already installed. Then copy the backed-up Thunderbird folder to c:\users\<yourid>\appdata\roaming That is the only guraranteed backup that works.

If there are missing files, first look in the profile to see if they are there. Do this in Windows File explorer in the ....thunderbird\profiles folder. They will normally be a set of two (e.g., inbox and inbox.msf) and local folders would be in Mail\Local Folders folder.