My outdoor electrical outlet has suddenly stopped working. Any suggestions?

This outlet powers my garden watering system (no wonder the plants have been looking dry and wilty), outdoor lights, and a small fountain. I checked the circuit breaker and all seems fine. Any other ideas suggestions?
THANKS EVERYONE! I reset the red GFI button on another outside outlet and that did the trick. [...]

How can I power a small fountain/pump 50 ft from an outlet?

I am making a 25-30 gallon container water garden with a couple goldfish. I would like to have a filter/fountain in it, but where it will be is 50′ from the closest electrical outlet. A solar fountain is out of budget, so I would like to run an outdoor extension cord under the ground. Years [...]