You rely on your watch to keep the time, hardly giving it a thought until one day when it decides to stop running. More often than not, that means it's time to change the battery. Replacing a watch battery requires removing the back of the watch, called the case back, in order to remove the old battery and insert a new one. Returning the case back to its normal spot is an uncomplicated task that you can perform in a short amount of time.

Set the watch face down on a soft surface, such as a computer mouse pad or a cloth. This protects the watch face from being scratched.

Place the case back on the watch. Some watches will have a rubber O-ring or gasket. If yours does, place this in position before placing the case back on.

Align the indent on the case back with the indent on the side of the watch and press on the case back gently with your thumbs until you hear a click. The case back is now in place.

Use a small standard screwdriver or a case back wrench, available at many hardware or watch repair stores, to close a case back that has several slots on the back. Use the screwdriver or the metal tips on the case back wrench to turn the slots on the case back in a counterclockwise direction. When all of the slots have been turned, the case back is in place.

Set the watch, if necessary.