Fog Light Switch problems of the 2009 Toyota Prius

When I turned on the car, the headlights would not turn on. Both lights had been fully operational the day before. Both high and low beams on both sides did not work, so it is definitely not the case that four separate bulbs or fuses all blew independently. I tried turning the headlight switch on and off several times, but this did not correct the problem. The fog lights do illuminate, but that is not enough illumination for safe driving in my area.