In hindsight, we may have been following the wrong trail. Those old prefs files are five years old, and any content would have been as you described. The missing profile was for another reason. If you still have the original content, we may be more successful. On your request for backup steps, here they are: I do this weekly. '''BACKUP''' # ensure thunderbird is not running # enter %appdata% in search window on task bar and press Enter key # this should open windows file explorer in Appdata\roaming folder # highlight the Thunderbird folder and copy to external media '''RESTORE''' # ensure thunderbird is installed and NOT running # enter %appdata% in search window on task bar and press Enter key # you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This will prompt to overwrite an existing folder of same name. allow it # start thunderbird and all should be there