I don't know how people do this! Why create a password you can't remember?
Anyway, if it's a user password, he may be able to log in as Administrator, and create another user account, or reset the password on the original. If he's actually forgotten the Admin password, I think things may become slightly more tricky, and as I don't have Windows 7, I wouldn't like to advise. Rodders may be able to help here.