When I turned on the hot water in my bathroom sink, nothing came out (the cold worked just fine). I checked the shut off valve, it was open, and all the connections were fine. I also checked all the other faucets in the house, and all the hot and cold worked fine. Is there something else I should check, what could be the problem?
Thanks

You could disconnect from the wall to determine if it is at the faucet or before.

I just tried that.. and it's before, there's no water. Any suggestions on what I should do next?

One handle or two? This tells me the hot inlet is clogged, the fix will vary depending on your answer to my question

Two handle

Shut off the supply to the hot from under the sink. Remove the handle and opull the stem or cartridge. Clean the stem/cartridge. Before reinstalling cover the valve hole with a towel and have someone else turn the suplly on/off quickly to flush the line.

If you disconnect the supply line and no water then you have problem with your angle valve, close the and angle valve all the way and open it see if it will help, if not then you need to shut your main water S/O valve, loosen the packing nut put a container under the angle valve and a towel over the angle valve ask some one to open the Main S/O valve slowly and see if the water is coming if it does then you need to replace the seal at the end of the stem or replace your Angle valve see the image below, good luck.

John

I believe he disconnect the supply line and no water so it tells me that the problem is with angle valve correct me if I missread his post #3, Thanks.

John

My bad, I missed that part, not the mixing valve, stop cock or before is clogged.

Thanks John, I'll try that next.