You might get lucky cleaning elec. conn., but often the only fix is to replace the horn(s) which are readily available at parts stores. Remember, you have a hi and lo note horn. You might check owners manual first for horn fuse and relay location and ensure they are good.
Turn steering wheel all the way to the right. Remove front half of plastic wheel well liner and jack up driver front of the car. Horn(s) should be visible in wheel well towards the front of the car. Unplug and unbolt.