When your watch not working properly or stopped working completely, the most likely cause maybe dead battery. The first step is to see if the battery needs to be replaced. Most watch batteries are designed to last about two years, but some quartz watches are designed to have an extended battery life and batteries for these watches can last up to three or more years. If you buy a battery online and try to change it yourself, you might damage you watch. Besides causing potential damage, by opening the watch yourself, you might void warranty on your watch. Moreover, it also runs the risk of damaging the watch case using inadequate tools. To replace the battery in your watch, we recommend you always visit an electronic store that provides watch battery replacement services.