It may be that, for whatever reason, Thunderbird encountered a problem at startup and decided that it needed a new profile. Try this: click help>troubleshootinginformation, scroll down to 'profiles' and click 'about:profiles' and your missing profile may be there to be selected. It would have your accounts and addressbook.

Thank You David, I'm having to Re-Type everything I had written, because after I selected the Screen Shot to attach, all the Text I'd written had Disappeared. I had some difficulty finding the Profiles, but I finally found where all the Files of Interest were "Hiding". I was a little disappointed because I thought the Profile I've been using for the past year or more would have been obvious from its Creation Date. But I guess the File must be "Dynamic" and Re-Writes Itself each time TB is used, as ALL Profiles were dated 2024-01-01.

Please note I've been Struggling with Pneumonia over the Christmas Period, so it may take me a day or to to finish this "Repair". I say this so you won't think me UNGRATEFUL for Clearing Off without Thanking You and Saying Good Bye, if you don't hear from me for a day or two.

I found a very Similar Question to mine, that you and "Toad Hall" answered, so I've been looking at the Advice Given, and I'll try that approach on my System. Fingers Crossed that it fixes my problem too.

Have a HAPPY NEW YEAR, and I hope to let you know how I went on, in a day or perhaps two. Robert Graham

The profile that ends release will be the new one. Profiles did not have release in the name until a couple of years ago. Older profiles were named simply default.

I'm back. I have 2 Profiles and when I see their FULL File Names, both have DEFAULT and RELEASE in their Files Names. As far as I can tell I have Selected EITHER Profile and selected the option to Start Thunder using that Profile and BOTH take me to CREATE A NEW ACCOUNT. I'm starting to Panic a little, as there were quite a few emails arrived around Christmas Time that MUST BE ACTIONED by the end of this week. IF I go ahead and CREATE a NEW ACCOUNT (I will new my Email Provider to supply all the Techy stuff like Port Addresses etc., will I DEFINITELY be able to Load all my Old Folders and emails Received and Sent into the New Account ? My original Account was called "microtech" but since the system started to think of me as a New User my Account Name has changed to "microtech2". Is this the root of my Problem and IF I can tell it I'm "microtech" wi;; all my "Old Stuff" Re-appear ?

That would indicate that there is a problem in the profiles. I do not have the expertise to diagnose exactly what the problem is, but if you create a new profile, the folders in Mail\local folders could be copied in, as well as the old addressbook, abook.sqlite. Another person may see this have have suggestions also.

I don't know if this Helps or Confuses, but I have found another THUNDERBIRD Account that links to my GMAIL Account and was created Several Years ago. The crazy thing is that when I tried to start Thunderbird using that account - it doesn't display any GMAIL messages and it also Invites me to Open a New Thunderbird Account.

I thought that I may end up having to Create a NEW Account, and then PRAY that it accepts and Displays all the Data from my previous A/c. But when I entered the details it tells me it Cannot Open my ZEN email account, suggesting the Password may be Incorrect, or some account parameters are wrong. I need to contact ZEN Support to find out what the Correct Settings are for TB to Talk to Them.

Thanks for your help David, and let's hope some Software Whizz takes up the Challenge.

It took a MONTH to get the Latest TB to work with my email Provider (and I REALLY DON'T LIKE the New Layout and the Task Changes that have SLOWED DOWN the checking of emails. But my BIGGEST PROBLEM concerns my DISAPPEARED Messages from my Previous TB.

I used the IMPORT TOOL in the new TB, which defaulted to Importing from a Previous TB, and then Re-Started TB, as Instructed. Although the Message Counter still only showed about 1K (New emails that had backed up at my email provider while TB wasn't working) I could immediately tell my "OLD" messages had loaded by the Time it was taking to Scroll Back through Messages. Sure enough, Important emails from Previous Years were once again available to me.  :)

I spent about half an hour Cleaning Up the most recent Messages, Deleting those of No Importance, and SPAM, (which is VERY SLOW and MESSY in the latest TB) and Archiving some, and then Closed TB.

When I re-opened TB a couple of hours later I found that ALL of the IMPORTED MESSAGES had DISAPPEARED !

When I tried to RE-IMPORT Them, the Process completed in a FLASH, as if there was NOTHING to Import, and sure enough, NOTHING had been Added to my Inbox.

Does the IMPORT Process COPY Messages into TB, or does it MOVE them ?

I suggest locating the old profile and then the message folders within and copying them to your active profile in the Mail\Local Folders folder and then starting Thunderbird to view. and then exit and do a full backup of the profile.