1998 Oldsmobile Achieva

Okay so I have a 98 oldsmobile achieva and I have been having problems to the point that now it won't even start. I had it towed to a shop to see what was wrong with it and it started up just fine. They checked for shortages and were'nt able to find anything wrong with it. I took it home and it was fine up until monday afternoon. It would act like it would start but nothing would happen. Now I went to start it and now the battery is drained and the key is stuck in the ignition; it wont let me turn it to take it out. I think it has something with this secruity thing that pops up when I used to try to start it. Please get back to me as soon as possible. Im a college student who drives and needs a car.