An electronic ballast is an essential part of a fluorescent lighting system. The ballast regulates and controls the flow of voltage that the fluorescent tube requires. Without the ballast, the light will not operate. Electronic ballasts are built into fluorescent lighting fixtures, but they will wear out or break on occasion, necessitating replacement.
Turn off the electrical power to the circuit that feeds the light. Turn this off at the circuit breaker panel for extra safety: It's easy for someone to accidentally flip a wall switch while you're working on the light.
Remove the cover of the lighting fixture and remove the bulbs---if necessary to access the ballast.
Clip the wires connected to the ballast with a set of wire cutters. Loosen and remove the screws holding the ballast in place and remove the ballast.
Take 1/2 inch of insulation off of the ends of the black and white wires that were connected to the ballast using a set of wire strippers.
Put the end of the black wire from Step 4 together with the end of the black wire connected to the ballast. Put a wire nut onto the ends and twist it until it's tight. Wrap a piece of electrical tape around the nut and the wires to hold them securely in place. Repeat the process with the two white wires.
Mount the new ballast onto the light fixture in place of the old one. Turn on the power to the circuit.