This should work: - click help>troubleshootinginformation - scroll down to 'profile folder' and click 'open profile' - exit thunderbird now - click the Mail folder - click the Local Folders folder - highlight the inbox and inbox.msf files - click the 'cut' button on File Explorer menu bar (or rightclick, select 'more options' and then select 'cut;) - change to the account folder (which is also a subfolder in Mail folder) and click the 'paste' button. - restart thunderbird and all should be okay.

Basically, the files "Inbox" and "Inbox.msf" need to be copied from the "Local Folders" location (or any other backup location) to the Account location. It worked.

Thank you!