Hot water suddenly stopped working at kitchen faucet
Turn off the hot water valve under the sink and remove the hot water hose to the faucet.  Put the end of the water hose into a pail and turn on the valve slowly.  If the water flows freely, then the problem is within the faucet.  If it doesn't then you have a blockage in the water hose.  Either try to clear it or purchase a new hose.  If it flows freely, then you should disassemble the faucet in accordance with the diagrams in the manual and look for some kind of blockage or a damaged part.