I searched this issue several ways to see if there was a fix for loss of sound on my Sharp LC-52D62U, but I found nothing.
Every so many on-off cycles, I will get no sound coming from my LC-52D62U via DirecTV set-top HD-DVR HDMI output. I tried various hard reboots of the box and tv, and was never sure how the sound would get restored since it didn't happen all that often. VERY frustrating.
Over the past year the loss of sound now might happen after just several turning the tv on & off. My consistent remedy has been:
1) Use original remote to change input to something other than the set-top.
2) Turn off the tv and leave it off until I hear a "thunk" sound.
3) Turn the tv back on and switch back to the set-top box input. Sound!
FYI- I have never done a firmware update.
It is a PIA but I am just trying to keep an otherwise decent set working until I get a HDR + DolbyVision + etc replacement [most likely an LG E6 -or- VIZIO P (once they ship with updated firmware)]. I just want to give back to AVS Forum members who help me with their info, tips and tricks.