Have you just upgraded your Thunderbird email software? To your horror, a first thing you may have seen upon restarting that program is that all your email messages and mail boxes have disappeared. Thunderbird needs to convert its database to a new format.
Some time later that program may have asked for your master password. You don’t remember ever using a master password and you usually typed individual passwords for each of your accounts. Perhaps you used a master password a long time ago and forgot about it. So what now you ask and how can you retrieve this master password?
You can try removing that master password by typing a following command without quotes into a windows run box “C:path to thunderbirdthunderbird.exe -chrome chrome://pippki/content/resetpassword.xul”. Click on “Start” then select “Run” and then type in something similar to C:\Program Files\..thunderbird.exe -chrome chrome://pippki/content/resetpassword.xul. An exact command to type into a “Run” box is an exact path to your thunderbird.exe file on your computer.
Another option is to delete a C:\Documents and Settings\User\ApplicationData\Thunderbird\Profiles.default/key3.db file from your thunderbird windows profile, which should prompt you to reset that master password when opening up this program. In above path “user” is your windows user name that you are currently logged into that has that password issue. You could also use Windows system restore point.
Restore it to a point before you upgraded thunderbird. This time you could go through thunderbird settings to disable a use of a master password and then try upgrading it again without a master password set.