Generally, reinstalling does not fix problems, but if you plan to reinstall, I suggest being extra safe. To do that, I suggest: - exit thunderbird - copy the profile elsewhere, whether to an external drive or to another place on disk. the profile is at c:\users\<yourid>\appdata\roaming\thunderbird - reinstall thunderbird and exit - copy the saved profile thunderbird folder to c:\users\<yourid>\appdata\roaming to overwrite the default thunderbird folder - restart thunderbird and everything will be there.