The more buttons and switches on the dashboard, the more likely you are to have one of these electrical accessories fail. Combined effects of vibration, weather, and age can eventually reveal the weakness of almost any electrical circuit. Most electrical circuits are well protected by a simple devise called a fuse, which is designed as an intentional "weak spot" in the electrical circuit. If the circuit is in danger of overheating or damaging other (more valuable) electrical components, the fuse element basically melts apart inside and shuts off the flow of electricity on that circuit. Until the fuse is replaced (and the root problem is repaired) the electrical devices on that circuit remain OFF.
Changing a fuse is as easy as changing a lightbulb, though there are variations among automotive fuses. Most American manufactured vehicles use a blade-type fuse, which you can just slide in & out. Fuses are designed and rated according to the safe power requirements of the circuit. Colors and numbers on fuses distinguish their amperage ratings. For example, a red "10" would be a "ten Amp" fuse. NEVER replace a blown fuse with a bigger, higher amperage fuse which will not properly protect expensive circuits or components. Make sure replacement fuses are properly rated according to your vehicle owner's manual.
When an electrical device stops working, first check for a possible blown fuse. Your vehicle owner's manual will tell you where to find the fuse panel or panels. Many fuse panels will have a removable cover, spare fuses, a fuse-puller, and a handy circuit identification chart. Use the owner's manual or circuit identification chart to locate and identify the suspected fuse and determine it's proper amperage rating. Fuses are easy to remove and replace as they just press into the fuse panel. With the fuse-puller (or your fingers) pull the fuse out for inspection.
Look through the transparent side of the colored plastic fuse to that it still has a thin strip of metal from one end to the other, without any noticeable breaks. Blown fuses will have all or a portion of the metal melted away inside.
You can also check a fuse uses a 12-volt test light, which is how service technicians do it efficiently. Simply clip the test light wire to an unpainted and electrically grounded metal surface. With the ignition key in the ON position, touch the test light probe to the small metal tabs on the top of each fuse. A good fuse will light the test light on BOTH small metal tabs on the fuse top. A light on only one metal tab of a fuse indicates a blown fuse. If the test light bulb does not light on ANY of the fuses, the problem is a poor clip connection (reattach the clip to another point, like the centre screw in an electrical receptacle)
If it is not apparent whether the fuse is good or bad, replace it with a new one. Fuses are not expensive. If the replaced fuse blows again, there is still an electrical circuit problem that will need further professional diagnosis and repair. Let the automotive technician which electrical devices do not work, and any unusual circumstances, like a recent traffic accident.