Start with checking the power cord connection and verify power to the Sound Bar.
Verify the device is plugged into the correct input on the back of the Sound Bar.
Cycle through all inputs on the Sound Bar (be sure to wait at least 5 seconds on each input for audio to be processed before moving on to the next input).
If still no audio, try connecting a different device to the Sound Bar.
NOTE: Some devices (TVs, Blu-ray, etc.) have audio out settings that also need to be adjusted to get these units to output an audio signal. Please refer to your device user manual or contact the manufacturer's tech support for help adjusting those settings.
For further troubleshooting assistance, please review this video: