clutch will not disengage
If it is full and there is no pressure then the hydralics have just quit working, the best thing to do is to replace the clutch master and slave cylinders as a set, then make sure all of the air is out of the system. This is assuming that the clutch componets are still in operating condition.
new clutch and pressure plate
So if it was installed correctly, and not backwards then the hydraulics have went bye bye.
Tennisshoes is right if the pressure plate was installed backwards the clutch will stay engaged, which means you will need to disassymble and reinstall the clutch. But check your slave cylinder first for proper operation. If you changed the clutch the slave cylinder will need to be replaced, the part cost around $20.
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