The laptop on my husband's hard drive was replaced and his Thunderbird password apparently not saved. (He had always logged in automatically to Thunderbird and did not remember the password.) When he attempted to download Thunderbird onto the new hard drive (same laptop), he was unable to do so without his password. He uses Comcast/Xfinity email; he does know his Comcast/Xfinity password. How does he download Thunderbird and regain access to his emails on Thunderbird?