Does any one know how to reset the relay switch for 1987 Chevrolet Asto door locks. When I press the door lock button I hear the switch but the doors don't lock.

Are you hearing the"switch" while inside the van? If so, then maybe the noise you are hearing is the solenoids. If so, they may just be needing some oiling. But that means removing/prying back the door panels.
Sometimes tho the solenoids loose strength and need replacement.