Audio on my GE television has went crazy

I get about 70 channels, about 10 channels the audio works fine, on some the audio is in spanish even though the captioning is in english, some of the channels have no sound at all and the rest the audio is just a loud noise like cable is out except the picture is perfect.
I have tried every thing on the menu but nothing helps. Its like the audio processer is out of wack.
It is about 9 years old and has a perfect picture, its a 31 inch screen and has the guide plus on it.
I hate to junk it if it can be repaired for not too much, or I can repair it myself.