Within the last week I have started having this problem with my laptop where I plug it in to my tv with the HDMI cable, I get the video but the sound plays through my laptop. In the sound settings the hdmi says that its not plugged in.
I have tried everything including rebooting the laptop with the hdmi plugged in and with it out. I have also tried rolling back and restoring my laptop and i have not installed any new software.
The only thing that works is uninstalling realtek audio driver and rebooting my laptop each time play something through my tv. I have tried this on my parents tv and it still happens so its got to be the laptop. The laptop is a custom laptop.