One of the most common reasons why solar lights may stop working is because the batteries need to be replaced. If your solar lights are not working, check to see if the batteries need to be replaced. Another common reason why solar lights may stop working is because they are not getting enough sunlight. Make sure that your solar lights are placed in an area where they will receive direct sunlight for at least six hours each day. If you live in an area with cloudy or foggy weather, your solar lights may not get enough sunlight to charge properly. Finally, make sure that the solar panel on your solar lights is clean and free of debris. A dirty solar panel can prevent the lights from charging properly.