my clutch goes all the way to the floor and does not disenguage , pedal stays in down position,

I just had the clutch assembly replaced, so i know that the pressure plate and the clutch plate are all brand new with under 3000 miles on it , well recently i went to use it and the pedal went all the way down to the floor, it did not spring back up, called mech who replaced clutch assembly and asked me to put it in gear while car is off, and try to start vehicle, if it lunged forward he said it was either the clutch slave cylinder or the clutch master, i did what he asked and sure as S@$% it lurched forward now how do i figure out which is the problem? is it the master or just the slave? do i replace both? and is this something i can do on my own with limited tools? trying to save money on labor costs if i can as i am mechanicly inclined and have done this type of work on a 74 toyota celica i onced owened and it was a simple fix.