Use your multi-meter to probe each connector. Set the multi-meter for DC volts and put the prongs of your multi-meter into the connector. It should read 12 volts. Check the wiring on any switch that has a low voltage reading. Tighten any loose connections, and clear away any corrosion. Test another switch. Take a switch from another door and plug it into the connectors on the malfunctioning door. If you are able to operate your window using this switch, then the original is bad and will need to be replaced. Buy a new switch. Contact your dealership or favorite parts store and get a new window switch. Install the new window switch. This can be done by plugging the connectors into the switch and popping the switch back into the door panel.
Bulbs, though, are probably No. 1 on the replacement list because they're used so much and because there are so many of them. Most cars, for example, have at least three bulbs and usually more on each side for brakes, taillights, backup lights, turn signals and side marker lights. In front, there are headlights, maybe separate high beams, frequently daytime running lights and fog lights, turn signals, "parking" lights and side markers. Chances are that over time at least a couple of those will burn out or stop working because of corrosion or excessive jostling from rough roads.
In case you don't know who take your car to for auto electrical repairs, you can ask for references from fellow motorists; ideally friends and relatives who are unlikely to mislead you in this (potentially sensitive) matter. As long as they have faced such situations before, they are likely to guide you on which service providers to visit; or at least which service providers to avoid.
When to Change Your Car's Battery. There are several signs that indicate the battery in your car is failing and needs to be replaced. Sluggish engine cranking and unusual electrical problems like flickering headlights are telltale signs of trouble, though they may also indicate problems with your car's alternator. You should also replace your battery if it is bulging or has a rotten egg smell.