Hot/Neutral Reverse Code

I've had two microwaves fail in the last few months. Both worked sporadic, and then not at all, and neither would work on a house plug after I took them out of the trailer.



My refrigerator works fine on gas, but not on electric.



I checked the plug for the microwave, and the refrigerator and get a Hot/Neutral Reverse code on my tester for both.



Googling tells me I probably have a loose ground wire somewhere.



Does anyone have advice for me?



I'm barely competent with basic electrical so don't even know where to begin.



Thanks,

Matt