Lost emails and accounts after windows upgrade.

After recent windows upgrade, Thunderbird initializes with a different look showing no accounts, does not ask for a master password. All as though it has been freshly installed and starts up from scratch or empty. I have followed a similar thread and deleted a global file as suggested with no success. However, in my case after digging around I found that Thunderbird is using C:\Users\TEMP\.................. whereas I have found all my lost accounts/folders/emails under C:\Users\"Username"\...................... There are other changes, losses I have noticed as though Windows re-initialized my user account with different settings. How can I correct the directory Thunderbird is pointing to?? Or perhaps I can replace the new Profile directory with a copy of the old one??