My car will not start

Okay, so you put the key in, turn it and get nothing? No dash lights no head lights? Just a dead car?
First thing I would check are the battery and battery connections. GM side terminal connections are known for corroding inside the rubber insulation and causing a no power situation. Check on both ends as a loose/poor ground or positive feed will act the same way.
Most parts stores will test the battery for free. You need battery voltage and cranking amps from the test.