Here is a relatively simple way to ascertain where the fault lies:
If you switch the engine off and depress the clutch pedal and it does not go into gear then there is problem with the gear box.
If you start the engine, when you depress the clutch pedal and it feels fine then the problem is with the clutch.
If it feels spongy or different to how it was before, there is a problem with the Slave or Master Cylinder.
If you find that the outcome of this test points to the gear box being the issue, it might be a good idea to change the fluid first as a stiff gear box usually means that the fluid is on it's way out, assuming that it has fluid.
Let us know how you get on buddy.
El