Firstly check with your neighbours to see if this is an area fault. You can also check on the national grid; you can check on this website https://www.ukpowernetworks.co.uk/power-cut. There may be something that has caused the electric to trip inside the house. You can check the fuse box and identify what has caused the outage. Often these can be re-engaged - please do not force switches up - if they cannot be re-engaged or the issue repeats itself please report as maintenance.