Fluorescent lighting is a bit more difficult to repair than incandescent lighting, where switching a bulb is usually enough to fix the issue. Fluorescent bulbs have a ballast that controls the flow of electricity into the bulb. When this ballast malfunctions, the light might flicker and create a buzzing sound. Usually the ballast can be replaced. Some fluorescent light varieties have ballasts that are more expensive than the entire system, so check whether the repair is worth the cost.
Turn off the electricity for the room at the electrical main switch.
Remove the ballast cover from the end of the light by removing the nuts with a socket wrench or by unclipping it. Removal of the ballast cover will vary between manufacturers.
Cut the wires connecting the ballast to the light using a pair of wire cutters. Make the cut several inches away from the ballast.
Remove the mounting nuts for the ballast from the unit using a socket wrench. Hold the ballast so that it doesn't fall.
Remove the ballast.
Put in the new ballast and screw in the nuts to hold it in place.
Connect the wires of the new ballast to the old wires using a wire nut. Hold the two wires together and twist the wire nut over the exposed portion of the wire. Replace the ballast cover and turn on the electricity.