Try this, hold the key on star and move the shifter from park all the way to low and back and forth a few times while holding the key on start. If at any time the starter engages except in park or neutral, the neutral safety switch is out of adjustment. Unless of course this has a manual trans.
If it still does nothing, turn on your headlights and dome light, watch the dome light it should be bright, if not charge the battery.
Now, with a bright dome light, turn the key to start and watch that dome light and listen for the starter and/or starter solenoid.
One of 4 things will happen. Normally, the dome light will dim slightly and the starter crank the engine over fast enough to start.
Nest will be the dome light does nothing at all and the starter does nothing, not even a click from the solenoid. That means there isn't any voltage making it to the starter and solenoid and could be the neutral safety switch, the ignition switch.
The 3rds thing is the dome light will dim heavy, the starter may turn over slow or the solenoid just click repeatedly. That means either the battery is dead or the starter bushings are worn causing the starter to drag and demand/pull too many amps from the battery.
The 4th is the dome light will go out completely and the starter will not turn over, the solenoid may just click the one time. that usually means a loose electrical connection from the battery to the starter or a bad solenoid, too.