Check the owner's manual for fuse locations, if your fuses are all good take a test light to the switches and see whatup. I'd say if one side went out its the switch but both at the same time makes that unlikely.
With that said, these switches are notorious for being bad, just ask the Super Duty/Excursion guys about the problems they have lol.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.