heater not working help

Hi all, the other night it rained and I had left the top off by accident. Anyway once dry I found my heater is not working. I can put the switch on defrost or the vents and they blow just fine but on the temp side switch regardless, on cold or hot side it blows cold air, and yes the A/C is off. Any advice to my prob. is greatly appreciated.

Thanks

Mark

Is it ever an accident to leave the top off? Or just a hope that we can drive to work topless.
Anyways that sucks, but would think something in the unit is wet, my son left my wife's patriot rear hatch open one night and it rained enough to fill up the spare tire well, and her gare adjar light would not go out till it finally dried out.