Please check if volume is turned up, please try to rotate the knob clockwise to the proper volume. Please check if volume of user device is turned down to minimum, please try turning it up. Please check if the connecting user device is playing audio correctly, otherwise you may need to try another device. Please check if the BT connection is disconnected, please refer to Q: Why can I not pair with the Bluetooth on my Tough System Music? Re-connect the device If there is still no sound, please take (TOUGH SYSTEM MUSIC + CHARGER) to an authorized service agent.