It was starting fine and driving fine, and last nite it wouldn't start. The lights come on, radio, ect...sounds like it wants to start but won't turn over..Fuel injection, 4 cylinder. Could it be a spark plug
If it is not turning over, then that means there is either low battery, bad solenoid, or bad starter. If it turns over but does not start, then it is one of three things, Spark, fuel or air. Just think in that dimension and you will find the problem.
"Won't turn over" is the key to your answer. The problem lies with the starter and/or battery circuit.
Make sure your battery terminals are clean and your battery is fully charged. Autozone-type stores will check your battery free of charge.
It's not normal for the starter or starter relay (the solenoid) to just suddenly stop working. Update your question if you are hearing a loud click and the headlights dim when you try to start it.
You don't state whether this is a manual or automatic transmission. If it has a manual transmission, it could be the clutch neutral safety switch. This is an electrical part attached to the clutch pedal under the drivers side of the dash. Part costs about $50.00 at Napa. Hope this helps.
I doubt it is a problem with the fuel pump as the fuel pump would no stop the engine from rotating.