This happened to me too! My car won't start after I parked it while I was in Dallas. It happened at night and I was ready to have it towed after we tried to jump start it but failed. I noticed that the headlights worked okay which means it's not the car battery. My friend drove me to Radioshack and we bought a battery for the keyfob and voila...the car starts perfectly!

Check your keyfob battery first when your car fails to start.