I,m a proud owner of a 46pfl9706 tv that have lost the sound on the TV.It was normal the first 3 weeks but now the sound have dissapered from both the blue-ray player and the tuner, still got sound from the Apple tv box,everything is connected via HDMI cables.
Any hints were i should start to solve the problem, i have tried to reinnstall all 3 components.
You could read about problem with disappearing sound on 46PFL9706T/12 via link below.
What you could do is to select another HDMI-input on the TV and back again, or if you use the built in tuner change TV-program and go back again.
If that donīt work you have another problem with the connections.