My 98 cavalier was making a rattling sound drove it then it made a thunk sound(like I hit something). Wouldn't start after that. When the key is turned it sounds like it wants to turn over but it doesn't. Any suggestions on what to start with?

how about an engine size?

engines a 2.3

The first thing I would do is remove the accessorie drive belt and see if the engine can be turned over with a wrench/socket on the crank pulley bolt. I would suspect not and the possibility that you broke the timing chain and its all wrapped around the crank pulley is my guess?