The lights are on but everything else just quit working entirely. I have replaced the Defrost Timer, Defrost Thermostate, and Start Relay. What else could it be??
Bad start relay on the side of the compressor?
Tap on the control panel to see if the cold control or some connector wire came loose. Rather rare, but the new defrost timer might be bad.
neither post really helped me to find a solution. 
I’m not very familiar with voltage testing but is it possible that I can isolate the bad component by testing different areas? If so please explain in simple terms. Thanks guys.
Did you try this?
You can try shorting the wires to the cold control behind the control panel.