My Goodman Central heat and air unit stopped working around 2:00 am this morning. The fan outside is not moving, blower inside, etc. nothing working. We had the thermostat turned to 72 degrees, fan on auto, and set on norm. I have tried turning fan to on position, set unit on emergency heat but nothing happens. I have also tried turning the unit to off position (not heat or cool) and to the cool position, nothing happens. The temperature has been in the low teens for several days. What could be the problem and is there anything I could try myself to fix the problem?

Have you check to make sure there is power/the breaker is on? If its electric furnace there would be a double ploe breaker, flip it off and back on. Gas would be a single breaker. If gas make sure the door/cover is in place,, get back to us and let us know the type furnace you have,, gas or electric

Start by checking you main panel circuit breakers to be sure they and the circuit breakers on the furnace are on. If you wish to reset them turn them completely off then back on.

You did not post the exact model number of your unit but you might check the inside unit to see if there is a fuse in the 24 volt low voltage section. If there is a fuse and it is defective it will need to be replaced with like same before the unit will operate. Many times the fuse blows if the thermostat has been changed and the wires touch in the wrong places. With the info you provided this is about all I can tell you at this time.
NOTE make sure the power is turned off when you go to check for that fuse.