It may have been renamed because I see there was already an abook.mab file there. The current version of THunderbird uses abook.sqlite. If that does not contain your email ids, you can import your mab contents at tools>import>importfromafile>inport addressbook>import the mab file.

Thanks for responding. The screenshot that I added above was that showed the abook.mab file was from File Explorer. When I followed your suggestion to import the mab file, the "Select address book file" window that opens just shows folders, not files, and it doesn't allow me to select a folder.

I'll attach 3 screenshots. The first is what appears when I open the "Select address book file" window. Then the other two show what appears if I back it out a level to the prior folder. But they all just show folders, not files that I can open/select. The file name box at the bottom of the Select window is blank and there's nothing I can select to open. (final screenshot) What am I missing? thanks

Are you using ver 102? That's the version I recommend. It allows importing a single file.

Yes, I had reverted to 91.13 in an attempt to resolve other problems, but I now upgraded to 102. Then I was able to import a single file as you said, and I have my address books back! Thank you very much!!!!

One additional question. I imported the mab files. There are also sqlite files (abook and history) that I could have selected to import instead. Would that have worked also? You said that sqlite is what Tbird is using now, so should I consider importing them? I'm happy with the results from restoring the mab files, but just wanted to check.

If you had both mab and sqlite, there is the possibility that the sqlite is more current. That is, any additions you made after Thunderbird switched sometime in the past to sqlite, the mab file would have been retained only for history purposes. If that applies to you, you may want to exit thunderbird, rename abook.sqlite and then copy your abook.sqlite backup to the profile and restart thunderbird to see if it is more current. BUT, if you're happy with what you have, I'd let it go. But the two may be far apart. MAB files haven't been updated in several releases. Going forward, your mab files are just baggage. I deleted mine.

Thanks. Just need to be clear. What do you mean more specifically by "rename abook.sqlite and then copy your abook.sqlite backup to the profile"? What/why should I rename it? And after I rename it, is that the backup that I should copy? And should I import it or copy it? Sorry to be so nit-picky but I don't want to mess it up.

Also, I believe the address books and lists previously displayed at the bottom of the window the # of contacts that were in that book or list, but that doesn't appear in 102. Is there a way to show that? Then I could compare the # of contacts in the mab file to the sqlite file.

I suggested renaming in case the abook.sqlite from backup didn't work, was corrupted, or was empty. I like to rename files being replaced when testing to ensure I can revert to where I was before. I do not know about ways to compare number of contacts.