First check the oil and see if you actually have any oil in the engine. If not then I would say you have seized up the engine by running the motor without oil to lubricate the parts. If the engine is just not turning over then I would check the battery and alternator and then the starter. If you have seized up the motor then you will have to rebuild the motor, to replace the parts that we're damaged. - first -check the battery ,alternator and then the starter((remove each one and check them separately to eliminate them as the problem)).they can be checked at most autoparts stores. If you can not drive the car then you will have to remove the parts and take them to the autoparts store to have it checked. To help understand how to remove these parts you can get a manual for most cars at the autoparts store or a local dealership that sells your brand of car.