First check All fuses.
Use a 12v test light or a multimeter set on DC volts and connect black lead to battery ground, turn key to on position and remove the two wires from the horns. Test the wires to both horns, one wire to each horn has a constant 12v.
Find these wires and connect them back to the horn, the other wires are grounds that are activated by the horn switch. If you have 12v going to the horns this means the horn button is probably bad, but let's be sure.
Connect a length of wire to to battery ground and touch the horn terminal that does not have the wire connected, make sure key is on. If the horn works thw switch is bad.