First thing I'd do...check your bulbs, not likely, but you'll be ticked if that's the culprit. If your bulbs are good, make sure their ground is still intact (not sure if they're grounded at the bulb or down a wire and grounded into the engine bay somehow. Regardless. Make sure it looks connected. Also check for voltage at the bulbs...if you're getting voltage at the bulbs, you either have a bad ground or your bulbs aren't getting a good connecting in the housing.
If you're not getting ~12v at the bulbs, follow the wiring back until you get ~12v. Whatever component your voltage stops at will be the culprit. If you get back to a mess of stuff... I can't help ya there...not without seeing it anyway, but if it's a simple problem, hopefully you won't get that far. You also could have a bad fog light switch and you'll need to replace it.