dragging sound then car shut off
 

Hi, i have a 2002 Audi A4 B6 with a 3.0 engine. i experienced a dragging sound , looked under the car and everything was fine. i stopped at a red light and my car died. i only had a mile to go so i started it back up and continued. i got half a mile as the dragging continued and as i was driving my car shut off and will not start back up. Any help please ?