97 Ford Escort- no heat/ac/defrost or vent fan. Nothing will turn on. Checked all the fuses including the ones under the hood. Worked perfect one day then nothing the next. What could be the problem and how do I fix it?

OK the HVAC system has several components that make it work.
The actual heat is the hot coolany from your engine that flows though a heater core.
The blower fan operates on 12 volts, and runs through a resistor to apply your fan speeds.
The selector to run heat, defrost, ect. runs off of the vehicles engine vacuum, and opens and closes diverter doors.
The A/C uses a pump at the engine, a condersor coil and several switches.
I would look to the HVAC switch controler. Check for voltage there.
Please let me know.