Hot water shut off valve will not allow any flow of water in my bathroom sink - not even a hiss or a trickle. Can I clean it or unclog it?

If you have a angle stop that's clogged turn the water off to the house and unscrew the nut on the stem,(see image) Back the stem and washer assembly out counterclockwise. Hold a pan over the open valve and have someone turn the water back on for a moment to flush out the valve. You should have a full stream when you do this If not click on back and tell us about it. Good luck, tom