Going to have to do the leg work. We honestly can't do anything over the internet. Start with the obvious which would be the fuses. TEST THEM don't just look at them as that can be a false reading use a tester and find out if there is a full connection through it. Next easiest thing would be to pull the horn out and either plug in a known working one, replace it because it is cheap, make some jumper wires and touch them to the positive/negative posts on the battery to see if it works, OR get a tester and see if it has any life left. If the fuses are known to be good and the horn is either replaced or found good, move on to the next thing which would be the wiring. Find out if it has power all the way up to the horn button.
Again, if the ribbon cable to the SRS is unplugged the horn won't work. The wires run through it. You NEED the airbag plugged in or you have to snip the horn wires out of it and resplice them to the horn button.
Last thing you can do is to go the extreme ghetto route and make your own horn button/switch and mount on the dash or console. Tap the switch into power and then to the horn.
