This house is 3 years old. All the house has hot and cold water but the one shower has only cold water. It is Moen and one handle in the center. Please help. Thanks

Shut the water off and open up the valve. Pull the cartridge and check and clean the inlet ports. Now, before you button up, turn the hot water on to flush out the supply and valve body. You should have a strong stream coming out of the open valve body. If not let me know. Good luck, Tom