As the horn and lights do not work, it must be the voltage feed to the switch. Check all connections at the switch and back through the loom to the fuse. This route will run through the ignition switch so - if the neutral light works, then feed is getting to the ignition switch. Check the Haynes manual wiring diagram to ensure you are checking the correct routing. Disconnect, check and clean, re-connect all connectors. Finally, check the distribution tag strip and battery connections. Once you find where the problem is, it will be an easy fix (that is one good thing about the older bikes).