Heater not working

I wonder if the heater control cable has come off the heater control valve. Ask a friend to operate the heater from hot to cold while you look at the heater control valve near the firewall in the engine compartment. The valve is in the heater hoses at the back of the engine compartment, two of them will go into the body of the car at the firewall.

Along with what Pat is recommending I would make sure you have coolant in the engine. I would also check to see if the blend door is working inside the vehicle. The blend door directs air to get heated or cooled before it comes out of the vents. You can check this by rotating the temperature knob and looking under the dash to see if the blend door motor is moving the blend door.