Step 1
Turn off the water supply to your bathroom.
Step 2
Pry off the cap of the handle over the problematic valve. Remove the screw holding the handle in place and pull the handle off.
Step 3
Grab the washer at the end of the valve with a pair of pliers and pull it off. Inspect it for signs of cracking or wear. Replace it if necessary.
Step 4
Inspect the valve for signs of rust or excessive white material -- mineral deposits -- if it is sticking or stuck. Clean the valve with a mixture of 50 percent white vinegar and 50 percent water to remove the white substance.
Step 5
Tape the ends of a wrench with plumber's tape. Grab the valve with the wrench and pull on it to remove it from the wall. Cover the valve with a cartridge puller, which comes with your replacement valve, if it is stuck. Wiggle the cartridge puller with your wrench till the valve comes free.
Step 6
Inspect all the washers and components of the valve. Replace individual components if necessary.
Step 7
Insert a new valve into the hole in the wall, aligning it properly with the water supply line. if cleaning or replacing individual parts did not do the trick. Reassemble the unit.