The answer to 'dimmer switch not working' is that there are several common causes, including a faulty dimmer switch, loose wiring connections, or a problem with the light bulbs. Symptoms may include the switch not turning the lights on or off, the lights flickering, or the switch feeling loose.
Some solutions you can try yourself include checking the wiring connections, replacing the light bulbs, or testing the switch with a multimeter. However, if the problem persists or you're not comfortable working with electrical components, it's best to call a licensed electrician to diagnose and fix the issue.