Step 1
Check your circuit breaker or fuse box. If there is a tripped breaker or blown fuse, reset the breaker or replace the fuse.
If there is a nonworking outlet and no fuse has blown or circuit breaker tripped, check for a tripped GFCI. A GFCI may be wired in a branch circuit where other outlets share the same circuit and fuse or breaker.
The nonworking outlet may be down the line from the GFCI and not even located near it. A branch circuit device does not protect anything plugged into it, but it does protect everything down-line from it.
Step 2
Locate the tripped GFCI. If you are having difficulty finding it, check a main floor guest bathroom, an entryway closet, a walk-in closet or the garage.
Until 1987 the code required only one GFCI to protect the whole house.
Step 3
Press the "Reset" button on the GFCI after you have located it. This will reset the outlet, and all outlets down-line from it should be working.
If it won't reset, press the "Test" button, then press the "Reset" button. If it doesn't stay reset, there is most likely a faulty outlet or device down-line from the GFCI.
If not, the GFCI device may be defective.