Fuse Board
If you find certain electrical devices not working such as lights on a whole foor, plug sockets, boiler etc it is always worth check the fuse board before you call someone out, replacing a fuse is simple a resolves a lot of issues!
Find your fuse box and have a look at the switches if you have a newer fuse box you will see a bank of switches as in the picture below, see if any are switched off and if so switch them back on, if it clicks back to off the fuse is more than likely blown, you will need to switch off the electricity in the property by flicking the large switch to off, you will then be able to removed the fuse housing and then replace the fuse, return the housing and switch back on the electricity
Older fuse boxes that look like the picture below, the premise is exactly the same as above but not as easy to determine which fuse has blown so its easier to replace all fuses