Why won't a 1992 Pontiac Grand Am start after washing the engine?

Did you cover the coil pack before washing? The answer is that in the washing process you got water into one or more parts of the electrical system, in effect grounding [or shorting] a part of the system, rendering it non-functional ["broken"]. "Usually," [though not always] this problem corrects itself ONCE the system has had time to TOTALLY dry out.