Did he change his password again after it was reset on playerdex? If not, then he could look for his password recovery email, which should still contain the randomly generated password. If that's the case (as in, he hasn't changed his password ever since he received his randomly generated password), then he should be able to use it to log into the game, as well as playerdex to change his password to something that he can remember more easily.
Otherwise, he may just have to attempt to reset it on playerdex again. Although the email cap is currently limited to sending out 100 emails a day (via playerdex), after it's done undergoing some testing, it should be raised, giving better luck with password recovery.