complete loss of sound on my Hitachi lcd television?

We still have perfect pictures via satellite, but no sound. Have tried all cables, switching sky box off at wall. But there isn't any sound through dvd or wii. Sky engineer tried new box, but still no sound.

So we are guessing television's gone fut!

Does anyone have any idea likely cost and ease of repair? Or whether we will simply have to get a new one?

Really appreciate feedback

many thanks