When I tried to get my mail using Thunderbird 10.0.2 I found out that I couldn't. I had formated my Ubuntu partition and reinstalled the system and when I tried to set up Thunderbird it told me that my password or user name for my Gmail account were wrong (and I knew that they were the correct ones). Today I found in the Google support page a solution that worked for me.

1º go here: http://www.google.com/accounts/DisplayUnlockCaptcha and continue with the verification step. You'll see that that action will have effect for 10 minutes.
2º open Thunderbird and enter your Name, Address and Password

That's all.

Google Support page: http://support.google.com/mail/bin/a...n&answer=14257