Electricity creates heat and wires get hot and can get very hot if a lot of electricity is passing through the wires and anything connected to the electrical wires can melt. And much more dangerous, it can cause a fire.
A great safety feature of an electrical system is the good old fuse. It is very simple yet can and does protect your entire home from many potential issues, fire being one of them. Basically a fuse is a very thin wire inside a glass container, connected at both ends to a metal end that connects to the electrical supply via a plug or fuse box generally.
The electrical supply passes through the fuse, it has no choice and does so to power an appliance, once it has gone through the power cable. If the fuse wire gets too hot it simply gives up and melts and therefore prevents the electricity from flowing through to the appliance, which is exactly what you want to happen, thus preventing overheating and a potential fire. This is very much like taking the plug out, a great safety feature.
So basically if there is a flow of power that is too much due to a fault in the mains or a surge of power, the fuse wire will melt and prevent the appliance being damaged and importantly ensuring it does not catch fire. And also this protects the user as power is cut immediately.
Each different fuse has a different amp rating, this rating shows the amount of electricity the fuse will allow before it melts and stops working. All of the appliances will have an amp rating that needs to be matched with the right fuse in your plug. Placing a fuse with a higher rating in a plug is not a good idea as it will allow too much electricity to go through before it melts and could cause permanent damage to your appliance.
Fuses must be replaces once they melt as they render your appliance useless as they are not able to allow electricity through to the appliance any more. Therefore if an appliance does not work anymore, it is good practice to unplug it and have a look at the fuse is ok. If in doubt replace the fuse. It is normally obvious that a fuse has melted or blown as there is a black residue in the fuse itself. If you notice any black residue, it is always better to replace it.
If a fuse continues to stop working after being replaced, It is good practice to get the advice of an electrician as it probably means there is a bigger issue with your electrical system.
In your plug there is a fuse, make sure you unplug your appliance before you do any checking of the plug or do any electrical fault finding. Then using a screwdriver, unscrew the plug’s main screw and remove the top. You will see the fuse in a copper bracket. Carefully ease the fuse out and replace it with a new fuse. Place the plug top back and screw it back on. And then plug it in again to see if you have fixed the problem.