The problem has happened before, but with a little wiggling of wires all lights, start button and other functions would come back until now.
Sounds like something is beyond wiggling.
I'd try disconnecting the ignition switch wiring coupler, clean, add dielectric grease, reinstall, and see what happens. This should be done on ALL connections as general maintainance on an old bike imo. Fuse boxes can cause problems as well. Wouldn't hurt to replace all the glass fuses with new ones after scuffing-up the metal contacts that they seat in.