There can be a couple of things that would shut down your vacuum cleaner. A wiring fault inside the cord retractor, power switch has failed, the motor armature has failed or the brushes on the motor have either worn down past their serviceable life or jammed (unless the motor has burned out - you would notice the smell). If you aren't electrically savvy I wouldn't attempt to disassemble your vacuum cleaner, but all of the above issues can be fixed at home. Take it into a shop for repairs. I have serviced the motors on a number of different vacuum cleaners successfully without having to spend money on repairs except to replace a bad on/off switch for a few dollars.