Both headlights out. Low and high beam

The Problem Symptoms Table in the Lighting System section of the Gen 2 Repair Manual describes 3 Suspected Areas if:

Low beam does not turn on (both sides)
1. Light control switch circuit
2. Headlight relay circuit
3. Main body ECU

There are 4 Suspected Areas if:

High beam does not turn on (both sides)
1. Light control switch circuit
2. Headlight relay circuit
3. DRL relay circuit (w/ DRL)
4. Main body ECU

Note that the manual makes the distinction that the circuits of the Light Control Switch and Headlight Relay could be at fault, not merely the switch or relay. Replacing the switch or relay (which you have apparently done) will not necessarily solve the problem, in fact, it is probably more common that the wiring rather than the switch or relay is at fault. (If the Main Body ECU needs to be replaced, you would probably be experiencing other problems as well as the ones you are having with your headlights). Most commonly, HID headlights will gradually begin to fail, meaning that one of them may go out, but can be turned on again by flicking the switch off and on. This seems to work if either the bulbs or the ballast is failing. From your description, I am guessing that is not the case. It sounds like they all went off at once and cannot be restored by flicking the switch. If you still have taillights, the switch itself cannot be at fault. You are then left with following the wires and testing their continuity from the switch to the relay and from the relay to the sockets. This might be something that is best left to a competent mechanic with knowledge of electrical systems in a car.

A couple of questions to help our understanding. Has the car ever been involved in a front-end accident? Have you had any problems with rodents chewing your wiring? Hopefully, some of the real experts in this forum can weigh in to help you.