Where is the horn located and what would stop it from working apart from the fuse which has been checked ok?

Answer 1

The horn itself may be defective. unplug the plug from the horn and use a testlight to see if there is power at the plug when someone presses the horn. If there is then remove the horn and power it up with jumper wires to a 12 volt power source (battery). If it works off the car check your ground. If it doesn't then try a new horn.
Don't know what kind of vehicle you have but most horns are located up front behind the grille area. The contacts at the steering wheel could be At Fault and also the horn relay.

Answer 2

Don't know what kind of vehicle you have but most horns are located up front behind the grille area. The contacts at the steering wheel could be at fault and also the horn relay.

Answer 3

If the horn is dead you should at least still hear the horn relay click. If you don't hear the horn relay click I would suspect the switch contacts in the steering wheel are dirty.