My Pontiac Grand Am has 104,000 miles on it and has been a wonderful car. Today when I tried to accelerate on a slight incline, the engine went 'clunk' and the car died. The battery turned over and all the dashboard lights lit up - the battery is only 2 years old. When the car did start and I put it in drive, the car would not move forward - it started going backwards. The car was towed to the dealership and once again someone tried to start it. The battery turned over but then stalled out. The car will not move. I was told it was the transmission.
The idea of it not moving when you placed it in gear does sound like a transmission issue. However, I have to ask why it stalled and is giving you trouble starting it. Was the check engine light on? Will the engine start now and run normally?