I know this is an old thread...
I HAVE the exact same problem. My clutch pedal went to the floor and I couldn't shift.
I checked my clutch fluid reservoir and it was bone dry. Refilled it and the the car was leaking clutch fluid big time. I took it to a shop, they said it looks like the clutch slave cylinder leaking. I wanted to find out more before getting anything fixed.
I refilled it again probably once more during the same day. The next day I fill it again in the morning.
During the day I go and buy a new slave cylinder (using a friends car). That night I go to fill it up again..WTF...no leak. I checked this morning too, no leak.
How the heck did that happen?? I'm still confused!
later,
Amir