The clutch is supposed to go in the engine, not in the car.

You likely have a clutch master cylinder or slave cylinder problem. Usually they get worn seals and need to be replaced. I can't remember how to narrow it down to one or the other, but someone will reply with that.

It's also possible that you are low on fluid or your clutch system needs to be bled, which could be the case if it only happened once. Bleed the system and see what happens; it's always cheaper to try that first before replacing the master or slave cylinder and that may be your only problem.