What would cause a 1994 Oldsmobile 88 royal engine not to turn over?

you need three things spark fuel and compression if one goes out or away it will never run you need to find out witch one is gone if spark is gone you need to look at electrical if fuel you need to look at fuel system be it pump or filter or electrical if it is compression it could be timing belt or chain depending on the motor i know kind or vived but its a good start for you