From https://support.mozilla.org/en-US/questions/1521095

I'm aware David replyed to me. Usually if I uninstall Thunderbird and reinstall thunderbird, my addresses are usually there, but this didn't happen this time. My folders weren't loading correctly so I thought TB may be currupt, so I felt it may be worthwhile uninstalling and reinstalling, but may be the worst idea unless there is a way to get the contacts back. I think it's pretty straight forward, what I hope for a goal or at least learn why my address contacts did not load. Usually I download TB from the Mozilla TB site, but it sceems necessary to get the app from the microsoft store. It just sceems like the address book recovery services are not there, so I need a older version.

From https://support.mozilla.org/en-US/questions/1521102

I figured TB was currupt. I decided to uninstal TB. Usually TB is downloaded from the Mozilla TB site. was necessary to download TB from the microsoft store, which caused me to lose my 300 addressbook contacts and the recovery address book service would not work allthough I received the message the address book was found on the server. Again the messages were not displaying at all in the all or inbox, or important folders which gave me the idea to uninstal and reinstal. I think the program is pretty straight forward, but maybe I wasn't clear about the messages not displaying in the all or inbox folder, that may be important.

If I understand correctly, you downloaded a new release from the MS store. The MS version installs to a different location, so any content would not be seen there. Generally, uninstalling and reinstalling can make a simple problem into a major one. You can check at c:\users\<yourid>\appdata\roaming\thunderbird\profiles to see if one of the folders there contains a file named abook.sqlite. If so, you can import it using tools>import>import from a file.