Why won't my radio work

There's two fuses; one for the switched 12 volts and one for the memory circuit. The memory circuit is typically tied in with something else that's always hot, like the interior lights, horn, or cigarette lighter. On a lot of newer cars the radio needs a turn-on signal from the Body Computer. Computers don't like reverse polarity from jumper cables hooked up backward, but it is very unlikely that computer could have gotten damaged and the radio is the only thing affected.

Here is how you install a new radio

https://youtu.be/jF_sDSS0n7I

Please run down this guide and report back.

Radio in 2004 ford f150 lariat is not working. Want replace the radio 4L3T-18C815-AM. Can I replace with any radio from say 2004 to 2008 fords? Took the truck to a radio repair shop and they checked the system and said it was the radio. I want to replace with a ford so I can retain the steering wheel controls. Want to buy a radio, but can I extend the replacement from other year f150s?

not sure on this, you may have to have the radio programmed to your truck. ask a dealer they would know.

My factory stereo system has power, all functions work on the display, but I get no sound. Occasionally it will play then stop again.

Most likely a fault in the amp in the unit or as it does work now and the a bad/loose speaker connection on the read of the dash unit.

You can test the speakers by holding down the three and six preset buttons until it enters test mode. If you hear no sound during that test, the head unit or cable are bad. I would pull the radio and double check the connections, then go from there.