Fluorescent lights require ballasts to regulate the electricity needed to activate the gas inside the fluorescent tube and produce light. Older fixtures use ballasts that require starters to preheat the tubes prior to the ballast taking over and keeping the tubes lit. Starters can fail and need replacing for the fixture to continue to work. Verify the wattage of the replacement starter to confirm it matches the wattage for the original starter and fixture.
Twist the starter either clockwise or counterclockwise one quarter-turn to release it from the starter socket. Locate the starter along the center of the fluorescent fixture. The starter is almost the same size in diameter as a quarter and is either white or silver.
Turn the power on to your fluorescent fixture at the switch. Turn the breaker on if you disconnected the electricity at the main breaker panel.