The answer to 'faucet not working' is that there could be several common causes, including a broken cartridge or washer, mineral buildup, or a problem with the faucet's internal mechanism. Symptoms may include the faucet dripping, not turning on at all, or only partially working.
To troubleshoot, you can first try cleaning the aerator and flushing the line to remove any debris. If that doesn't work, you may need to replace the washers, springs, or cartridge. However, if the faucet is older or the issue is more complex, it's usually best to call a professional plumber to diagnose and repair the problem properly.