When a fuse has excessive current passing through it, a small piece of metal inside the fuse will melt, preventing the power from continuing to pass through the wire.
In some cases the top of the fuse is glass and many people think that you can just look at the Metal piece inside to see if it is broken. This is not always the case as it may be detached at the end.
The best way to deal with a suspected blown fuse is to simply replace it. If the power is restored, great! If not, then you should call an electrician with troubleshooting skills.
