In your /home there is a hidden folder .thunderbird rename it to thunderbird-old.
You may want to export your address book first
Start Thunderbird then reconfigure your settings and it will make a new .thunderbird. If it does not get all you e-mails you can go to .thunderbird-old there will be a folder named something like f9pc1ei9.default.
Open it and copy everything in the mail folder to you new .thunderbird.
Thunderbird must be closed when you do this