With the headlights on, when you turn the key, do they dim substantially? If so battery has insufficient charge to engage starter solenoid. If that's ok, have you tried starting it in neutral., that would obviate a faulty neutral start switch when they shifter is in park. If the battery has sufficient power and there is no audible click of the starter solenoid engaging, it sounds like a faulty start switch. Try the neutral start, if that fails, it's not the switch. Sorry can't help any further.