Need Help! Car won't turn over

Great. Next time try to use precise terms because I was totally confused.
"Starter works" means it turns, so usually the engine will too.
"Won't turn over" means the engine doesn't turn.
At that point, I am thinking "starter turns, engine doesn't", so starter gear must not be moving forward - thus a bad starter.
"won't catch" means maybe above?, but now sounds like you meant "cylinders don't fire".