The answer to 'water softener not working' is that there are several common causes, including a lack of salt, a malfunctioning control valve, or a problem with the resin bed. Symptoms may include hard water, low water pressure, or the softener not cycling properly.
To troubleshoot, first check the salt level and refill the brine tank if needed. You can also try cleaning the control valve or regenerating the resin bed. However, if the issue persists, it's best to call a professional plumber to diagnose and repair the problem, as water softeners can be complex and require specialized knowledge to service.