Instructions
Place your Xbox 360 headset on the charging cradle and charge the battery. If your headset was working fine and then suddenly stopped working, the problem with the battery could simply be that it has been depleted of all energy. Charging your battery back up to full capacity will allow you to use the headset again.
Make sure that the headset battery is operating at room temperature. If you store your headset near a window, for example, and the battery was in direct sunlight for an extended period of time, this could cause the battery to become too hot to work properly. Take your headset out of the sun and leave it in a room-temperature location until it cools back down and attempt to use it again.
Purchase a replacement battery for your headset from an electronics store. Because the Xbox 360 headset uses rechargeable batteries, eventually the battery will need to be replaced. It will lose its ability to hold a charge for more than a few minutes, rendering the headset unusable. Replacement batteries can be purchased at stores like Best Buy and GameStop and online at Amazon.com or Microsoft's own online store.