My radio/cd player turns on,searches for and stores channels, the cd player loads and displays the track being read but there is absolutley no sound. It appears to function correctly, but there is no volume, not even a hint of a hiss! the car also has sat nav with no sound!
Any suggestions?

 

It could be your amp, or a loose harness. What system do you have? When I was adding a sub to my system and went to test it I forgot and left the blue harness unplugged and naturally no sound would come out of the speakers.

 

I'm in the UK, its the 6 stack bose cd/radio and the original sat nav that was standard fittment here.I dont think anything has been apart but I could be wrong.
I'm having engine problems so the battery has been disconnected quite a few times, I was wondering if the radio code would need to be entered to make it work, but as everything is working apart from the sound that seems unlikley.

 

Have you checked all your fuses? If those are all good and the amp is fine... I'm out of ideas.

 

A similar situation occured to me when disconnected the battery. I could not turn on the radio and only the CD player was working. I had sound though. The next time I started the car everything was operating properly.