Cause: If PC’s (desktop/laptop) sound output is not set to HDMI terminal, there is no sound output from TV.
Check sound/audio device properties from the PC’s Control Panel.
Sound setting in PC) [Control Panel] → [All Control Panel Items] → [Sound] → [Playback] tab
① Select Sound from the Windows’ Control Panel
② Select LG TV from the device list, and right-click the mouse to set as default device
③ If the LG TV is shown on the list, contact the PC manufacturer to check the driver installation status