Stop trying to force it, you will eventually damage the gearbox internally.
You need to bleed the clutch. This will most likely restore normal function. How long it lasts will be the next issue.
There is a bleed nipple exactly for this job and the process is detailed elsewhere on this forum.
Also, assuming the fluid level is ok in the master cylinder, try wedging the pedal down overnight with a bit of wood. This can allow air to rise up out of the pipework.
Assuming bleeding it does work and there is not another problem with the clutch plate, then you need to find out why it needed bleeding. Air will have got in - there are only a few possibilities.....
1-In through the master cylinder - this means the fluid level is too low and the master cylinder is drawing air. You need to know why the fluid level dropped. Has it failed and leaking into the cabin?, has it leaked where the pipe joins the body? Alternatively (unlikely I would think) it could be drawing air in past the pushrod seal.
2-Leaking at the quick release joint where master and slave join together. Myself and a few others have had problems with this after clutch replacement due to shonky, pish quality, cheap, bollox parts. Mostly made by Borg and Beck. Check the join to see if its wet - if fluid is leaking out, air is possibly seeping in.
3-Drawing in air at the slave cylinder, probably leaking fluid out too. You will need the undertray off and check to see if hydraulic fluid is dripping from the bottom of the clutch bellhousing.
In case of 1, you might get away with a new master cylinder. If its two or three, you are **** out of luck and need to drop the gearbox off and change the slave cylinder.
