If you have no pressure, you have air in the system, a bad clutch master cylinder, bad slave cylinder or a leak in the lines/fittings (that allowed fluid out and air in)
Replacing the whole system is cheap if you do it yourself.
edit: Oh, I searched your questions and see this is a series of questions. You didn't post that.
The slave cylinder mounted on the tranny should actuate a lever/fork/arm that is spring loaded. when you changed the clutch, this assembly must be oriented correctly to push back on the slave cylinder piston, which in turn, will push back the pressure to your pedal. Push the little piston in the slave back in to place to help reset your pedal. Press the pedal while someone looks at the slave cylinder to see if the piston is coming out. If it is, but then won't retract under pressure of the clutch fork, the problem is in the clutch replacement. Basically, what I'm saying you need to test is the return spring mechanism.
Replacing the whole system is cheap if you do it yourself.
edit: Oh, I searched your questions and see this is a series of questions. You didn't post that.
The slave cylinder mounted on the tranny should actuate a lever/fork/arm that is spring loaded. when you changed the clutch, this assembly must be oriented correctly to push back on the slave cylinder piston, which in turn, will push back the pressure to your pedal. Push the little piston in the slave back in to place to help reset your pedal. Press the pedal while someone looks at the slave cylinder to see if the piston is coming out. If it is, but then won't retract under pressure of the clutch fork, the problem is in the clutch replacement. Basically, what I'm saying you need to test is the return spring mechanism.