Does the clutch feel as though it's working when you press the pedal?
If so, its possible that the plate has stuck to the flywheel as you suggest. If you have room you could try starting up in gear, the higher the better, and while driving with the clutch held down, snatch on and off the throttle. This will usually jolt it free. Otherwise, towing in high gear, again with the pedal held down may also work. If trying this approach, make sure the engine cannot start. Be careful whichever way you try!
Tom
June 2009