Diagnosis
The soundbar is on the wrong input source. It doesn't auto-switch reliably with some TVs, especially if you've switched TV inputs.
How to Fix It
Grab the remote. Press the INPUTTV for optical or HDMI for the ARC connection. The front panel display will show the active source. Wait a few seconds after selecting the correct one.
If That Didn't Work
For HDMI ARC: Go into your TV's sound settings and manually set 'Audio Out' to 'HDMI ARC' (or similar) and turn OFF the TV's internal speakers. For optical: Ensure the optical cable is fully seated (you'll see a red light) and in TV settings, set audio format to PCM, not Dolby Digital, for basic compatibility.
Heads Up
The HDMI ARC port on the soundbar is the one labeled TV (ARC). You must use that specific port and a compatible HDMI cable. The other HDMI port is for passthrough only.