DIAGNOSIS This is almost always an input or signal handshake issue. The soundbar is powered on and receiving a signal from your TV (hence the display), but it's not decoding the audio format correctly or is set to the wrong input.
FIX Let's walk through the signal chain. 1) Check the input on the soundbar. Press the 'Input' button on the remote and cycle through until you see 'TV' or 'HDMI' on the display, depending on how you have it connected. 2) If you're using HDMI ARC/eARC, power everything down. Unplug the HDMI cable from both the TV and soundbar, wait a minute, then plug it back in firmly. Power the TV on first, then the soundbar. 3) On your TV, dive into the sound settings menu. Ensure the audio output is set to 'External Speaker' or 'Audio System', and the digital audio format is set to 'Auto' or 'PCM' for a basic test.
IF THAT DIDN'T WORK Try a basic reset on the soundbar's audio settings. While it's on, press and hold the Volume Down and Input buttons on the soundbar itself (not the remote) for about 5 seconds until the display resets. This won't erase your settings but can clear a glitch.
HEADS UP If you're passing a 4K/120Hz or VRR signal from a game console through the soundbar to the TV, some older HDMI cables can't handle the bandwidth and drop the audio. A certified Ultra High Speed HDMI cable is a must for that setup.