If you want a cheap temporary fix where you don't have to tear apart anything as far as steering wheel or anything, go to advance or autozone and get a universal pushstart horn button.
You already know the horn is on with fuse in, horn is off with fuse out.
Also get an inline fuse holder and crimp on end connectors that will fit down into the socket where the fuse goes in the fuse panel. Also get some butt connectors. Also get a roll of 16 guage wire.
Take the crimp on connector, crimp it to the one end of the inline fuse holder. Take the fuse out of the fuse panel for the horn, put it in the inline fuse holder. Take that connector and plug into the side of the horn fuse socket that already has power. Then get some wire and connect to the other end of your inline fuse with the butt connector, have the wire long enough to reach up to your dash wherever you want to install the horn button. Hook up to your horn button, then hook up another wire from the other side of the horn button long enough to reach down to the other side of the horn fuse socket, put the connector on it, push into the socket.
Now your horn will work when you push the new button you bought, unless the problem you have now ever fixes itself on its own, then you would have to push that button and your steering wheel in at the same time.