need help with clutch

[nissanguy13]

Okay I know Im going to get flamed for this. Im running low on time, and Ive been working so much I havent had time to tear the car a part. Okay heres the problem, my friend left me with his 91 240sx se. He just put a new clutch in it before he gave it to me. I drove it twice and everything was fine. Just recently I went to start it up and drive it down to a shop so I could work on it and the clutch pedal was touching the floor board. I put the pedal back in the up position and put pressure on it. As soon as I did that it flopped back to the floor board. It has absolutely no pressure in the pedal. It has plenty of fluid and like I said a new clutch. Only thing I can think of is the master cylinder or slave cyllinder? Is there anything else that could factor into this problem? Like when he put the new clutch in he forgot to do something, or could of messed something up? I wouldn't be writing this if I had time to tear it apart, but It only has temp. registration on it until the end of this month. So I need to narrow down the problems quick, instead of searching all day. I need to get it running asap, so I can fix the other problems and get it smogged.
Thanks to anyone that helps.