Look at the main breaker for the house, to see if it's in the "On" position. If the main breaker is off, there should be no power in the home. If it's in the "Off" position, turn on the switch.
Check to see if the break in question flips back to the "Off" position when you try to turn it on. If it does, there is a short in the circuit that must be corrected by an electrician.
Touch the non-contact voltage detector to the electrical wire that's connected to the breaker. If the detector illuminates or beeps, there is power in the wire, and the problem is downstream of this point. If the detector finds no electricity and the breaker is in the "On" position, the breaker is faulty and must be replaced.
Follow the electrical wire along its path, until you reach a connection to an outlet, device or other branch circuit.
Hold the electrical detector to the wire's insulation before and after the connection. If there is power before the connection but no power after, the device is possibly faulty and must be replaced. Repeat this process, checking all the connections in the circuit until you locate the problem.