The hot water is not working in my kitchen?

You may need a new cartridge for the faucet, or you may have a blockage in the hose or valve under the sink. You'll need to detach the hose from the faucet and turn the valve back on into a bucket to see if the blockage shoots into the bucket. If you get lots of water, but no or very little debris, then you need a new faucet or a cartridge for the faucet. If no water comes from the hose, then remove the valve and attach a garden hose to the pipe with a hose clamp. Then see if any debris ends up in the sink when you turn the main shut-off back on in the basement or wherever the water meter is. You'll need a new valve then, at least.