Turn the key to ignition and NOT start. Turn on your headlights
get out and look see how bright they are. Bright means the battery might be ok. Dull means it's flat.
Remember some cars the headlights that only work with the ignition on. So if you see side lights but no head lights you could have either a faulty ingintion switch or the ignition fuse has blown. if it is the fuse and you replace it and it blows again you will have to put it in the hands of an auto electrician to find out what the fault is. The other thing to look for is the small wires on the top of the starter motor [the solinoid] one might have come loose or the feed wire to the ignition has broken my daughter had this happen on her car.
Bob
October 2005