What would cause the car to crank but not turn over?

There are many things that can make it crank over but not start. It could be a lack of fuel, it could be a lack of spark. There are many sensors like the crank shaft & cam shaft sensors that, if they go bad will not send the signal to the computer that the engine is turning so the computer never puts fuel in the cylinder. It should not be very difficult to diagnose if you get it to a shop that has the equipement to test it properly.