Ok, what may have happened was a Thunderbird update that may have been interrupted by an anti-virus program. If you do run an antivirus (other than the free Windows Defender), it may help for the future to see if it has settings to bypass email. BUT, to focus on your issue: - when you see the pane to create an email account, that is an indication that the profile has problems and Thunderbird set up a new profile. - if menu bar isn't visible, click the alt key to see it. then, click help>troubleshooting information, scroll down left side to 'profile folder' and click 'open profile' - exit thunderbird - note the name of folder, as that is the current thunderbird profile - back up one folder in File Explorer. That should place you at the ...thunderbird/profiles folder. - look in the folder to see if there are other profiles. If so, click inside to see if your account is there. It will be in the Mail folder of POP or the Imapmail folder for IMAP. Any local folders would be in the Mail\Local Folders folder. - post screenshots if you find your accounts and we can go from there.

Thanks for the answer....in each profile I see Local Folder and Root folder, which one are you sggesting I open to view profiles?

I have opened root directory and in there i see some profiles, one of which has mail accts but they are the ones ive just added as had to start from clean slate.......the other profiles do not have Mail nor Imap mail.....so seems profile has gone somehow. When I open Local directory and see profiles non have mail nor imap................when this happened.......yesterday i bought a new PC, installed Thunderbird, googled how to move profiles.......opened Profile folder with thunderbird shut, copied the foler....went to new machine found default foler, went up 3 levels to Thunderbird and pasted the copied folder....when i went back to source machine to open thunderbird all was gone......and on new machine when i opened TB no accts were there either

Also i seem to be able ot see inside of thunderbird, profiles i have set up on a different machine.......i didnt think thunderbird could sync between PCs, but I created a new profille on new machine and now on old machine i can see it, but says.......This profile is in use in another application and cannot be deleted

Is the old PC still available? If so, do this - on old PC, with Thunderbird not running, copy c:\users\<yourid>\appdata\roaming\thunderbird to external drive - on new PC, with thunderbird installed but not running - copy the exported Thunderbird folder to c:\users\<yourid>\appdata\roaming to overwrite the existing thunderbird folder - restart thunderbird on new PC

Thats exactly what i did yesterday , as described above.....then when i started new thunderbird, nothing and when i started old thunderbird nothing

No, those are different steps than what you described. I encourage you to do the steps I suggested.

I'm sorry but your steps and my steps seem identical. Copied the thunderbird folder to new PC and overwrote the one there

Okay, I am assuming these are Windows PCs and that Thunderbird works properly on old PC. If you view the profiles.ini file in the thunderbird folder on the external drive you copied to, it will show the name of the active profile folder, the name of which usually ends in default or default-release . That is the profile that was copied to new PC and you should see it intact on the new PC in the ...appdata\roaming\thunderbird\profiles folder. if you view the profiles.ini on the new PC, it should look exactly like what was on old PC, since you copied it directly. Please review and let me know what you find. Thanks.