Horn How do you fix horn on motorcycle?

I replaced my stock horn with one of these:

http://www.harborfreight.com/bad-boy-air-horn-94117.html#.UxM25fldVAA

To fix your horn is easy, there are some excellent pills out there.
The bikes horn though is different, you will need a small test light or multy meter,
Check if there is power to the wire plugged onto the horn, ignition on
The horn needs direct power to one terminal, and the other terminal shorts to earth through the button.
If there is power and the other wire connects to earth, when the button is pressed you probably need a new horn( not that expensive)
If there is no power check the fuse
If the second wire doesnt connect to earth when the button pressed there may be a problem in the handle switch.
There can also be a problem in the wiring if it has been damaged in the steering stop etc
Sometimes the horn can just be stuck and a small tap on the horn with the button pressed can start it.
If the horn button it a bit corroded in the contacts, hold it in and wiggle it a bit, can clear the corrosion.

Sometime easier to just check the fuse then buy a new horn, before chasing down the wires and switches

you will have to trace the wires back and with the aid os a multimeter find where the fault is.