help!!! wont start

ok, a couple of months ago, i was driving my 95 lumina(3.1 liter engine) when the engine just quite running and it just kept coasting. i tried to start it up, but it just makes a clicking sound, and doensn't roll over. before i towed it home, i tried to put a new battery in it, but that didn't work. when i got it home i bought a new starter for it, still doesn't work, got the alternator checked, still doesn't work.i'm thinking that the motor seized up, but that doesn't make sense because ther was enough oil in it cause i had just put oil in it a couple days before. if anyone has any ideas of what it might be, i'd really love to know.

Try turning the engine over by hand. If it rolls over, then it's not seized. The next thing to check is to see if you are getting power to the "s" terminal on the starter solenoid with the key in the start position. If not, try starting it in neutral instead of park. If it works in neutral, or you still have no power at the "s" terminal, you have a bad neutral safety switch.