It may be that thunderbird installed a fresh profile. Reinstall Thunderbird, if you haven't already. Then try this:

1. click help>troubleshootinginformation, scroll down to 'profile folder' and click 'open folder', then back up one folder in windows file explorer and see what other profiles are in the profiles folder. If there is a second one, open it and see if there is a file named abook.sqlite (the addressbook) that looks to have a recent date. also check the imapmail folder for a possible IMAP account or the Mail folder for a possible POP account. If you find anything, you have found your missing profile
2. click help>troubleshootinginformation, scrolll down to 'profiles' and click 'about:profiles', and see you can 'launch' the found profile. If not, click the 'create profile' button, then click next, then enter a short name for profile (such as PROFILE), then click the choose button to select the profile you just confirmed and click finish and launch

If that doesn't work, but the appdata\thunderbird folders is there, I would browse the profiles to see if you can locate any of the items I mentioned, including abook.sqlite, and possible account data in either imapmail or mail folders. When thunderbird isn't running, those files can be copied to the active proflle (abook.sqlite to the root folder and the message folders to Mail\Local Folders folder.

If that doesn't work, you can always post screenshots of the profiles you locate.

"If you do a search in the c:\users\<yourid>\appdata\roaming\thunderbird\profiles folder, you may find abook.sqlite and history.sqlite. These are the technical filenames of the addresssbook and the collected addressbook. You can import them with tools>import>importfromafile. This sometimes happens, that thunderbird creates a new profile and some content is left behind. No, this does not happen to everyone and is likely a glitch wherein an update was interrupted by another program, such as an antivirus product."

This might help. search for "abook.sqlite". Found it in a file, C:/windows.old. look for last oldest.

Oh, forgot to add. then import to address book.