If it is indeed the case that you can turn the key, but the starter wont engage you could try jumping the solenoid. You do this going under the hood and finding the starter solenoid, and connecting a jumper from the positive battery terminal to the hot lead on the solenoid. You have to be careful that the vehicle is in park/neutral (if it’s manuel). This will not work if it has anti-theft cause the fuel injectors won’t turn on. In summery: Turn the vehicle to the on position with the key and then jump the starter. Be carfull of moving parts. You may want to use an alligator clip on the starter, and just touch the other end to the battery. Good luck. Post back if you have any more questions and to let me know if it worked.