I had sound and image since first set-up. Suddenly, I have no sound? The only possibility of any change I made was inadvertently pushing the wrong button on my Yamaha remote. But I don't know which one I pushed. I think it was set up to use the ARC. I only use the internet from my computer to the receiver HDMI connection for watching stuff on my TV. So I use HDMI4 PC and the AV I'm not sure was on AV1? And I don't know what the Audio was on: audio 1 or audio 2? All I know at this point is the Mute is Off. Please help.