Fluorescent light bulbs are in the shape of a tube with electrical connectors on each end. The tube contains a small amount of mercury and argon gas. When electrical current runs through the tube, the mercury and gas combination illuminate, producing light. The tube gets its electrical current from the ballast, which on some fixtures is controlled by a fuse or a "starter." If your fluorescent tubes are flickering or will not come on, you may need to replace the fuse.
Shut off the electrical current to the circuit your fluorescent light is on at the main breaker box.
Remove the plastic cover from the light fixture by pressing in on one side of the cover until it releases from the fixture. Lower the cover and place it aside where it will not get broken. Skip this step if your light fixture does not have a cover.
Remove the bulbs by twisting them out of their holder to see if the fuse is mounted underneath them. The fuse is a small metal cylindrical-shaped device mounted inside the light fixture.
Remove the fuse by pushing it in slightly while rotating it counterclockwise.
Replace the fuse with one of the same wattage rating to avoid damage to your light fixture. Press the new fuse into the mounting hole and turn it clockwise until it locks into place. Replace the bulbs if you removed them earlier.
Replace the plastic fixture cover by sliding one end of it into the slots on one side of the fixture. Press down on the other end of the cover and push it into the opposite side of the fixture. Do not bend the cover too far or it may crack or break.
Turn the circuit breaker back on at the breaker box. Test your light fixture.
Replacement fuses for your fluorescent fixture are available at hardware stores.
If you cannot locate a fuse in your light fixture, it is probably a modern unit that does not have a fuse. The problem with your fixture may be a faulty ballast or blown bulbs.