Headlights, instrument cluster lights, tail lights, and dome light all stopped working at once?

When the car has many failures like this and the circuits were not really "Connect" or integrated, I would start testing/ checking with the Power and Ground distribution diagrams, then go to each system, do the same thing then see what they have in common in power and Ground and then start the troubleshooting for each system.

You have not provided enough information like which fuse, fusible link etc has been replaced or checked. You even did not say what did you do a Voltage drop on or specified how all of those system or lights reacted ..

What else are not working on the car? What happen or being done prior things shot to ..he**? Any added system before hand?

Check the fuses under the hood