He'll have to get a new password, and that can only be done on line.
Tell him to make a new character and then catch me or one of a coders on line, and we'll help him change the password for the old char.
Or he can note or mail me the name of his old char, and I can put a temporary password on it and let him know what it is, so he can change it to whatever he likes next time he logs on.