How do I fix this fluorescent light?
Besides the bulb, there are two other common failure points:  the inductive ballast (which limits current and, for long tubes, is a step up auto-transformer) and a preheat/starter switch (not a capacitor).

Both those components are replaceable, though it may be difficult to find them.  In the 1940s through the 1970s, they were available at every hardware and electrical supply store, but since standard florescent fixtures have now been completely obsolesced by compact florescent (CFL) and LEDs, compatible components are now uncommon.

If you can't find parts or they are expensive, this might be a good opportunity to replace the light fixture with a modern one.  It will be about three times more efficient, quieter, more reliable, and more easily repairable.  They should be quite reasonably priced too due to significant competition.