Don't tear anything down yet. First off, you said the car won't go in gear. You don't need a clutch to put a car in gear. With the engine off, see if you can shift into all the gears. If you can get into what at least feels like a gear, turn the car over with the clutch in and with the plug wires off and see if it lurches forward or stays put. If it stays put, put the plug wire back on and start the car in gear with the cluth in.
Let the clutch out and see if the car dives. If nothing happens when you let the clutch out, you are not in gear or your clutch is engaged. If your clutch is engaged, you should be able to shift into all gears with the car ideling and your foot off the clutch pedal. If it grinds when you try to shift with it it running and foot off the clutch, you know the clutch is not stuck in engaged postion. It's all just process of elimination stuff.
Fist thing, like I said, it to ensure you actually are in gear.