2006 hhr passenger side windshield wiper not moving but drivers side is fine??

First remove the complete passenger side wiper check and make sure splines on wiper are not stripped. If this is not the problem It could be a linkage bar from the wiper motor to the wiper off or disconected. Since both wipers share the same motor if one works the other should. Check this by removing both wipers and then "Cawl" (little black piece between the hood and windshield underneath the wipers) Underneath the cawl you should be able to see the windshield wiper motor, and linkage bar to both of the wipers. See if the bar is disconected from the passenger side. If it is than reconnect it. These are the only two possible scenarios.