Many thanks for your replies.
I have my WDTV Live cabled through a Yamaha RXV375 Amp via HDMI Cables all working great until suddenly NO Sound but great picture.
It is also conected to server and Internet.
My first step was to check the firmware through Set Up, which was the latest according to the web.
Next was to revert to “Factory Settings”.
I have by the way already recieved a response from WD overnight…
They advised to do all the above plus use the reset button on the base of the unit as well as test with another HDMI Cable.
If non of these work they sugest that the unit has probably failed and would require replaceing as warranty has expired last year.
I know there has been some adverse comment about WD response but I can only complement them in my case. Well done WD.
I will update on the outcomes.