Why wont my radio work in my car?

Why doesn't my car radio work?

• in my 1991 lincoln town car my audio system doesn't work at all...i tried to change the head unit with 3 others. still no sound. it has 2 amps but doesn't look like there's anything wrong with them. no radio sound and i don't know what to do first. should i replace the whole system or is it like a blown fuse? i checked all the fuses under the dash and under the hood. is there any others i don't know about? there's to the amp and head unit but nothing works. how can i check?

• Answer:

  check the fuses to the amps and behind the head unit if thats not it check your grounds and, see if you have power to your radio