When an outlet does not have power you have several options, from checking tripped circuit breakers to replacing faulty outlets. The average person can do many of these repairs but should call a qualified electrician he does not feel confident in making these repairs himself.
Circuit breakers are protect an electrical circuit and will trip if too much current passes through the device. Go to the circuit breaker and check if it has been tripped. A red tab will be evident and the breaker switch will be easy to move. Flip the breaker back to the "off" position and flip it back on.
Some outlets are controlled by a nearby switch. Check to see that the switch in the "on" position.
Sometimes an outlet can go bad from excess use. To check that the outlet is okay, turn the circuit breakers off and remove the screws from the outlet. Remove the outlet and verify that the wires are tight and secure. Turn the breaker on and measure the voltage across the outlet. The voltage should be 120 volts AC. If it is, turn the breaker off and replace the outlet.
Some outlets have a Ground Fault Interrupt (GFI) built into the outlet. These special outlets are similar to a circuit breaker and trip when there is an excess of current in the circuit. Check to see if the circuit trip light is on or the the "Reset" button is out. If so, press the "Reset" button.