Having an electrical problem? Some problems have simple solutions which you can probably do yourself. If it is listed here try it.
TRIPPED CIRCUIT BREAKER
There is no electrical power in some areas? It is probably a tripped circuit breaker. Find the panel and check the circuit breakers.
On newer breakers there are three positions for the handle (on, off, tripped). There is a marking of "ON" or "1" for the on position, "OFF" or "0" for the off position. The tripped position will be somewhere in between on and off positions. If you find a breaker in this position it has tripped. To reset it move the handle to off then to on.
Some older breakers will have the handle in the off position if tripped. To reset move the handle to the on position.
Sometimes it may not be obvious if a breaker has tripped and the handle would look as if in the on position. In this case you can try turning off all circuit breakers and back on. Be advised that this operation will cut power to each circuit temporarily so make sure that sensitive devices such as computers or TVs are off when doing this.
Still have the same problem after reset or the circuit breaker will not reset? You may need to contact an electrician to further diagnose and repair the problem. Also check the tripped GFCI section below since this may be causing the issue.
Some outlets in kitchen, bathroom, or maybe outside are not working? This may be caused by a tripped Ground Fault Circuit Interrupter (GFCI) receptacle. Find the GFCI and press the reset button to reset them. Note that the GFCI receptacle may be at a different location than the outlets which do not have power.
The GFCI will not reset or trips again? If there are devices or appliances plugged into outlet that don't have power, unplug them and try resetting the GFCI again. If the reset is successful, try plugging the devices or appliances back. Upon plugging in if a device or appliance causes GFCI to trip, there is a wiring issue with that device or appliance, potentially dangerous condition, and such shall be repaired or replaced before use.
If the above does not solve the situation and the GFCI trips, even with nothing plugged in, it is time to call an electrician to diagnose and repair the problem.
BAD LIGHT BULBS
So you turn on the switch but the light does not come on. Do not assume that you have a major electrical problem. There is much higher probability that the cause is a failed light bulb rather than en electrical problem.
Most light bulbs failures happen during startup when there is very high current draw, and this puts stress on internal light bulb components. This means that the light bulb will not even emit light when failing.
Replace the light bulb in the fixture with know good bulb to test. Request electrical service if replacing the light bulb does not solve the issue.