Unfortunately, Thunderbird saves its settings where Microsoft says it should (typically '''c:\Users\{you}\AppData\Roaming\Thunderbird…''') and for some bizarre reason, no-one (including Microsoft) thinks to include this in backups. Unless you changed the profile location yourself, I don't think you'll find anything useful under My Documents. Here is some information on the profile and what Thunderbird stores in it: https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data Firefox uses a very similar system. That will be under…\AppData\Roaming\… too.