2004 chevy cavalier died and wont start again

If the car has ,,, Compression, fuel and a properly time spark ... it has to start ....no, if's and or but's .. it must start (I'm an engineer) Lets review what happened ... When you turned around you shifted the Transmission .... there is a switch in that transmission that prevents starting the car unless it is in the proper position. You said the car does crank so it appears the switch is OK .... but the switch is the only thing that may be related to starting and you did actuate the switch when changing gears ,,, just to be on the safe side ,,,, check that switch

thank you very much Tom and just pulled the valve head, zero compression but the timing chain is moving and rockers and everything are going, kinda clueless as to why its not generating compression. if the crank is turning the timing chain and the cams it should generate compression, we tested all four cylinders, no compression on any of them... also for future reference what is that switch called

Me thinks the Head gasket could be blown but it doesn't make sense that all 4 cylinders have no compression .. good one minute then all 4 blown the next. If the cylinders had no compression then the engine would spin like a rocket when you engaged the starter. You would be able to turn the engine by hand with very little effort. ,,, for proof, crank the engine with the plugs in then crank it with all the plugs removed, Get a second compression tester because your about to get Balls deep in a repair that to me doesn't make sense. I;m not saying it's not possible because I had a car the timing chain jumped and it bent all the valves ,, but >> The switch is called a neutral safety switch