Cannot find my password to let me in the account

If you mean the password for you email account (Gmail, Yahoo, etc.) you ''might'' be able to see it in <Settings | Privacy & Security | Passwords | Saved Passwords>. However, depending on your server authentication settings, you may only see a randomized token, which appears as a random string of characters, but not your actual password. If so, and you have no other record of your password, you will have to reset it on your email provider's web site. You should then be prompted for the new password when you next start Thunderbird.