You mean the one in the plug? It's easy (as long as you have a replacement fuse to hand. You will need a 3, a 5 or a 13 amp fuse.
Unscrew the plug and take apart the casing.
I don't think you will have to remove any of the wires, but if you do, just make sure you remember which colour went where, so you put them back in the right place.
Then you just flick out the old fuse and replace it with the new one. Put everything back and screw the plug back together.
But more to the point - what were you doing using a blender to make garlic butter?! All you need to do is mash the garlic into soft butter! A fork is all it will take. (And much less washing up as well!)
OK, You need to get a new fuse Get a screwdriver to take the back of the plug off when you take it off LOOK at where each colour wire goes. I haven;'t changed one for years but it used to be blue for left and brown for right (there's a L in blue and an R in Brown is how I used to remember) unscrew the wires put new fuse in put wires back put back on that's it