If all of your power fails the first thing to do is to check if it is a whole area power cut, the easiest way at night to do this is to look out the window and see if the street lights are working, if they are off then your whole area could be suffering from a power cut, the only thing you can do is ring the electricity board and inform them that your area has lost power and then use torches not candles for light. Try to open fridges and freezers as little as you can, every time you open them you allow warm air in. If your power goes off in the day time ask a neighbour if they have lost power, if they have not or if the street lights are still working read on. You need to go to where you fuse / MCB board is, firstly make sure that the main switch is in the on position, make sure that you check that any RCDs are turned on and have not tripped. RCDs can be identified by the "T" or "Test" button that they have on them. If you have an RCD and it has tripped try resetting it. If the RCD trips again consult Allsuns Electrical for advice.. If the RCD has not tripped or there is no RCD within your installation you need to consult Allsuns Electrical for advice on what the fault could be.