I am making a guess here, so follow me through: Mu guess is that thunderbird created a fresh profile, and you set your account up in that new profile, even though the old profile still exists. Try this: - click help>troubleshootinginformation - scroll down to 'profiles' and click 'about:profiles: - your old profile may appear. click the 'open folder' button to investigate - now, click the Mail folder and then the Local Folder to see if there are message folders there. - if present, Exit thunderbird first. Then, with windows file explorer, COPY (not move) the entire contents and store them in the Mail\Local Folders folder of the active profile.