The way your heater works is by using water from the engines cooling system.when you select warm on the controls a valve mounted in the water that runs from the engine bay through the firewall to a small radiator mounted behind the dashboard. That valve is possibly what failed

If the heater hoses are hot, odds are the blend door that controls air temp is stuck or otherwise not moving. There are three blend doors under the dash.
You may need a shop manual to get the instructions on how to test them.