Personal audio players are one of the most popular types of electronic devices. To use a personal audio player, you need headphones, and headphones sometimes stop working. Most annoying of all is when headphones only partially stop working; music plays in one ear, but not the other. Fortunately, the source of this problem is simple to locate. There are only a few places where a headphone can break, and finding them is a simple process.
Open your personal media player's settings and check the "Balance" setting. This tells the device how much signal to send to each ear. Adjust the balance to the middle, and play audio. If this does not fix the problem, check the jack on the player. Press the headphone plug firmly into the jack, and lightly move it around with your thumb. If you hear crackling or the jack wobbles, the jack is probably damaged.
Test your headphones on another device with a headphone jack, such as a computer or another personal media player. If the problem remains, check the cups of the headphones for audio controls. Some headphones come with discrete audio controls for each ear: these can be accidentally turned down in the course of normal use. Check any other controls on the headphones. Controls on the cord may include separate volume controls for each channel.
Examine the cable of the headphones carefully. Look for cracks in the insulation, sharp kinks in the wire which will not unbend, or wire strands protruding from the insulation. Examine where the wire splits into two. Listen for any rattling inside the cups of the headphones. If there are no visible signs of damage, there is probably a short somewhere in the wire.