Is freezing in Maine...my Sephias heat stopped working?Any ideas please?!

[micmac]

I have a 2000 Kia Sephia.It has lots of the same issues as lots of you(bad breaks,excessive tire & break noise & wear,fasle front seatbelt latch,does not start in very cold weather-which isnt for me a battery issue-I can only start mine if I literally heat the car up-I used a huge outdoor blow heater in front of the hood for about 5 minutes.That dry gas stuff doesnt help-maybe someone will find that helpful)
But I need help- my heater stopped working.Nothing,at all seems to be wrong.We put in a new thermostat.heater core seems fine-everything is holding fluid.Its not overheating.But it blows cold air.It happened for the first time over the summer,it didnt matter much then.In the early fall,i suddenly had working heat.It stayed like that until someone unknowingly turned my hot/cold knob down to cold,and it never came back to hot.any ideas?

[micmac]

Well-got it fixed! Its a little white knob under the passenger side of the dash.Sticks down about an inch.You can see it is not moving back to position from cold to hot.