Candaysee

I don't know anything about cars so someone please help. My car (Chevy Cavalier, 1997) just stopped working on me. It's not the battery....the lights and radio are on. It will not go in any gear. I actually had to put the emergency brake on for the car to stop rolling backward. The engine won't start and when I turn the key nothing happens...no clicking sound or anything. Do you think it's the tranmission? If it is how much should I expect to pay? How long does it usually take to fix? Would it be smarter to get a new/used car?
Please help!!!!