Hi I have a 1977 mobile home. Lived here about a year now. Last winter I used the furnace and threw the summer used the air conditioner. Well come this winter the furnace won't work and it said "reverse politary" so a family friend switched around the wires to make it right. And along with that around the same time my lights dim& flicker. The furnace will turn on and lights get really bright. The fridge and furnace almost seem to be battling for energy, when one is making noise(warming up/kicking on) the other is barly working, fridge kicks on the furnace is barly blowing air.
I plugged a tester into the plug in (same one I had air conditioner in) amd it read "hot/neutral reverse".
Lights dim till little appliances turn on suuch as TV, coffee pot, playstation even a haor straightener.
Just yesturday my TV made a noise I look over and its smoking almost caught fire (it was bejng used to play the playstation, dontknow if that matters)
Washer would kick on and shut the playstatio off.
Furnace when not on makes a like warming up sound and many other crazy sounds.
Please help I know it is a very dangerous situation I just don't have the money right now and its very scary. I don't get why furnace and all was fine last winter.

Ive heard I might not have a ground on my house, I heard I need more breakers , I heard wires are just crossed or loose and its an easy fix. I just wish I knew and am hoping its not a very expensive job.

There is nothing here for you to do... please find a professional electrician. I think the answer is a loose neutral which should not be too costly to repair.
No guessing, call a pro...

No guessing, call a pro...
I agree.
The "reversed polarity" diagnosis of those little plug in testers is not reliable. The symptoms you describe sound like a loose connection in the main panel or at the disconnect on the pole. The loose connection could be the hot or the neutral.
Call the pro. Have him reverse the change the friend made.
Does your outlets have two holes or three?