Old profiles would be in c:\users\<yourid>\appdata\roaming\thunderbird\profiles

David, I already looked there and what I saw is the profiles I mentioned in the initial posting. What happened to all the other profiles missing between 2019 and this past week?

Is there an alternative way to retrieve lost emails and folders other than thru profiles?

On your first question, different profiles are created rarely. I have used the same one for a decade or more. So, there may not be profiles other than the ones you've seen. On your second question, Thunderbird only stores messages within the account or local folders of a profile.

Done of my visible profiles contain messages and folders since 2019. Question remains, how can I get these?

THey may be gone. You mentioned your prior thunderbird was misbehaving and you lost messages.

One day I have over 3000 messages and corresponding folders from years 2011 to 2024 and the next day after reloading Thunderbird because it was stalled, they are all gone. How can anyone safely use Thunderbird with this kind of performance. I hesitate to ever use Thunderbird again and I certainly would not recommend it to anyone.

I think this list of previous questions, which all appear to be describing a similar vein relevant here. https://support.mozilla.org/en-US/user/shydubren/questions

Particularly this one. https://support.mozilla.org/en-US/questions/1460458

You apparently had an issue with the program hanging and you thought to reinstall to fix it. I have never understood how doing the same thing over again is expected to fix anything, but reinstall folk do. As you have observed it failed rather spectacularly and is frequently the cause of far more trouble than existed before the decision to blow it away and start again.

I have never seen any mention of the actual error you received. So I am left guessing, as I expect David was. but I am also guessing you thought to install and older version. My guess is it was a complaint about the versions of Thunderbird being used in the profile as described in this support article. https://support.mozilla.org/en-US/kb/dedicated-profile-thunderbird-installation

I also think you fail to actually understand what a profile is. It is not some time based thing. I have one profile with my last 20 years worth of emails in. If you regularly have new profiles, even in Firefox as you suggest, you have other problem outside of Thunderbird. Quite probably related to antivirus products and system optimization software. Both do a pretty good job of messing up Thunderbird from time to time including causing the creation of a new profile folder. This process in Thunderbird is generally signaled by it asking for you to set up your accounts over again when it starts.

So you have created another version of Thunderbird and set up your accounts all over again now is my guess. So what you are asking to do is abandon all of that and go back to the profile you were using when this all started. I can not tell you which to use because you have not itemized the profiles you have in your profile folder. So all I can do is point you to the relevant documentation.

https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#w_start-the-profile-manager-when-thunderbird-is-closed

Very old profiles tend to be named default with the ones created post version 68 having names like default-release

If I was looking for an old profile in the profiles list, I would be looking for one that contained a prefs.js file that was a the most recent before the reinstall. that files is not written everyday, but every account setting change is stored there.

When you uninstall, you are asked if you want to delete the program or everything. Choosing everything will delete the profile as you have requested that. Are you sure you are not looking for something you actually chose to delete?

It is easy to blame the software, but I find almost all true data loss situations are caused by user decisions, choices to remove mail from a server or delete the program and supporting data, not software itself.