If you cannot turn on the device or the device is not recognized by the PC after connecting the device, unplug the device from the PC and reset it by simultaneously holding both the - and + volume buttons for approximately 4 seconds. If the connection is unstable and the device is repeatedly disconnected, plug the device into a USB port connected directly to the motherboard of the PC. If the PC does not recognize COWON C2 because the device is out of battery power, either recharge the device or connect it to a power source before reconnecting to the PC.