If the pedal is moving the arm back and forth, and has some resistance, the disc may be stuck to either the plate or the flywheel. You can try popping it. Get car pointed down the street or a long driveway, start car in neutral, let engine warm up, turn it off, put car in first gear (reverse works too but harder to steer and do the following), keep clutch pedal fully depressed (released), start car. It will start rolling. Jab the gas pedal a few times, being alert to get off the gas in a hurry once it releases. I've also seen it done by getting up some speed and slamming on the brakes (clutch released). Take appropriate precautions for all of this.