Did you immediately try 'Edit' > 'Undo'

In your Profile folder under 'Mail' folder there will be 'Local Folders' mail account.

NOTE: close Thunderbird before making any changes to Profile folder.

In Local Folders mail account:

• You should see 'Resources' as a file with a 'Resources.msf' file.

This contains the 'Resources' folder emails.

• You should also see 'Resources.sbd' file folder.

Prior to moving things this 'Resources.sbd' file folder should have contained:

• 'Software' as a file and 'Software.msf' file.

This would contain the emails in the Software folder.

• You would also see a 'Software .sbd' file folder.

This Software .sbd' file folder should contain the files that were sub folders to Software. Both the filename with emails and the same filename .msf indexing file

As you have created a backup. Open you Profile folder and try to locate files and move them into the correct positions.

Local Folders folder

• ->'Resources' as a file
• ->'Resources.msf' file.
• ->'Resources.sbd' file folder.
• -> ->'Software' as a file
• -> ->'Software.msf' file.
• -> ->'Software .sbd' file folder.
• -> -> ->more files with their .msf file..follow the same structure as above

Thanks so much for that last reply, but I just can't seem to get things back. Somewhere along the way something clearly got really messed up, and I just can't seem to figure out what it is. I even ran Piriform's Recuva program to try to recover deleted files and restore them in the appropriate places, but no matter what I do I can't seem to get them to show up when I fire up Thunderbird (even though, as far as I can tell, I've got all the files/folders structured correctly).

I just don't know what happened -- something totally screwed up, big time -- but I do have a small consolation in this...

I bought a new computer the other day, and still have the old one, where everything should still be fine -- just a few days old, of course, and only missing maybe a handful of emails (hopefully nothing too important!) -- and so I guess I'll just copy what I need to from there, and make do with whatever I can get. It's a total pain in the butt, though, to unhook my mouse/keyboard/monitor and switch it to the old computer (the way I have things set up), so I'll do that later... when I'm not feeling so utterly exasperated. ;)

Thanks so much for your help! I really wish I knew what went wrong, and why I can't seem to get it back, despite great effort to get it all structured correctly, etc.

Wish me luck that I at least recover most of what I had before (whenever I'm up to the task)! Cheers! ;)

PS. Oh, yes, I did immediately try doing an undo, but right after moving that "Software" folder (and all it's sub-folders) I changed the name of it, too. Then I tried moving a new message from my in-box to a new folder in there, but strangely I couldn't seem to move it. And THEN I thought maybe I'd try moving that whole "Software" folder back where it was before that (under "Resources"), and then things only started going downhill from there... and then there seemed to be no "undo" possible at all. I guess I must have confused my computer -- not sure if that makes me smarter or dumber than a computer (ha ha). ;)

Can you find

Local Folders folder

   ->'Resources' as a file 

If yes, simply copy it to a location elsewhere to Thunderbird profile, install the import export tools https://addons.mozilla.org/en-US/thunderbird/addon/importexporttools/ and import the mails (That file is the actual mail, everything else is not needed to recover the actual folder content.)

Oh, that sounds promising -- or it sounded promising, at least. I installed it, but when I go under Tools -> Import (which I presume is where I'm supposed to go), it gives me the option to import "everything", or just mail, or just address book, etc., but no matter what I click on then the next option is to import from Eudora (which I still have installed for my old, old emails), Outlook, or Outlook Express (neither of which I have installed). There's no option to import "from file" or whatever.

I can't find any other import option other than via Tools -> Import. Am I doing something wrong???

re: 'via Tools -> Import. Am I doing something wrong??? '

Yes, Tools -> Import is the wrong one

you need to use 'Tools' > 'ImportExportTool'

Oh, wow, I think that did the trick! I'm not sure now if I may have lost anything, but indeed I was able to import a whole bunch of mailboxes (and the emails they contained) back into Thunderbird. I'll have to check on the old computer if I somehow lost any mailboxes in the process, but if I did... well, I'll just copy those off the old computer to the new, and import those, too!

Thank you so much, Toad-Hall! I wouldn't go as far as to say you're a life-saver, but you're most certainly an email/mailbox-saver, for sure! Many, many thanks for your time and trouble! :)))

PS... I'm trying to mark this as solved, but can't seem to figure out where/how. In my email notification about your last reply, there's a button to do so, but when I click it all I get is an error page -- and I don't see anything here on this page to do so. I don't know if it's critical that I mark it as solved now, but naturally it'd be nice to do so, of course.