I have a Sony Vaio laptop that used to play sound through my LG TV but now it will not. It only shows picture and plays sound through the laptop still. When I go to playback devices it shows the TV on there but it says that is working properly but not plugged in. The option to set the TV to the default playback device is grayed out along with the test option. The other device on playback is just the laptop speakers, Realtek. I've tried disabling and re-enabling, restarting, and using different HDMI cables, nothing works. I need some help figuring this out.
It's usually the Intel graphics drivers you have to reinstall to try to fix HDMI sound issues. It has nothing to do with the Realtek sound driver. HDMI carries both video and audio, and the HDMI out is controlled by the Intel graphics chip. The graphics driver adds a dummy audio device, which pipes sound to the graphics card, which sends it on over HDMI.
The Intel drivers have been flaky about this for years. You may have to revert back to an older version of the graphics drivers to get sound working on the TV. If/when you get it working, I suggest not updating the Intel graphics drivers again.