password

There is no "Thunderbird email password". Are you referring to your email provider's password? If so, there's a slight possibility, depending on how your email account is set up, that you can view their password in Saved Passwords (see <Accounts | Privacy & Security | Passwords | Saved Passwords>.) If you don't find it there and you have no other record of it, you will probably have to reset your password on your email provider's web site.