How can i fix the sound on my Toshiba TV Model No. 23W330DB?

I moved house and plugged the TV into the aerial and am using freeview. Yesterday morning (28/8/12) the TV was working perfectly fine. I then turned it on again in the evening and the sound had stopped working. I have a perfect picture but no sound whatsoever. I have tried mute and un-mute; turning the volume right up; resetting the whole TV (3 times); retuning the freeview channels (4 times); trying a different aerial cable; and also trying to attach external speakers. Nothing has worked at all and I am getting frustrated as the TV is only about 5 years old. Please Help!