Sounds like the clutch master or slave cylinder has decided to fold. Se the brake and block it and with engine off,crawl under there and have a helper step on the clutch pedal and watch the rod and arm at the slave and see what it/s doing
Somebody correct me if I'm remembering wrong here, but if it's not moving and you feel pedal pressure, slave is bad, not moving and no pedal pressure, master bad.
If it's moving a full throw with no symptoms at the pedal, could be pilot bearing locked up making the input shaft continue turning with the engine.