Question to heat and cooling installed into my recently acquired home built in 1997: I have an Amana Furnace and Air Conditioner in my home, my furnace unit has a sticker that reads " converted to propane " can this unit be altered to be a heat and air unit using no propane?

Yes it can be converted back to natural gas, which means changing the burner orifices and regulator spring in the gas valve as well as the pilot orifice if there is a pilot.
You could also just use it as an air mover for a heat pump if you wanted.