Sometimes caps die. Electrolytes can go bad, build up hydrogen and cause the cap to vent, a spike can pierce the insulators, interconnect leads between terminals and foils can fail. Fortunately, most times they die open or with a high resistance, or their capacitance changes too much with electrolyte age to be useful. Occasionally they short though, and that will cause a breaker/fuse to go.
Caps are also cheap, as far as appliance components go.
You should probably just replace it and move on, unless you have some pattern of multiple failures.
Make a note of the values of the original failed unit (microfarads and voltage) to have handy in the event you ever need another one. The rule of replacement is that you want to match as close as possible; you can go higher on voltage, but stay as close as possible on uf.
If you note the value of the original unit, you'll be best prepared to get another, as the repair guys may simply use what they have on the truck. That's not a really bad thing in itself, but if it happens a few times, then the replacements may get further and further from the original value.
