My thermostat is set for heat and is on auto butit was only blowing cold air I turned it off for about an hour and put heat on80 turned thermostat back on and now it is blowing hot air what can be wrong

Your contactor may have failed. If you don't know what you are doing with repairing a furnace would suggest you contact a repair person. With all the deep freezing weather we've had this definitely puts a strain on your heating system causing failures of parts. There is no quick fix for this problem. The only way it will get better is when each component is tested to see which one failed.

Reading back on your posts it sounds like your gas furnace needs repaired as a component failed. Could be the thermocouple or something else.