my entire turn signal system stopped working?

suspect multifunction switch.

I had the same problem with my 1999 Cougar. I fixed it... here's how. Get a screwdriver, it may have been a torx or phillips (i forgot). Take off the cover of the rear of your steering wheel; basically the cover of the steering shaft, between the steering wheel and the dash pod. Its only 3 or 4 screws. You will also need to remove the panel UNDER the steering wheel to some degree. You will need to wiggle and fiddle around to get the cover off where the Ignition Key is but it'll come off. Now... sitting in your drivers seat as normal... on the left side there is a square relay switch, about the size of a 9v battery. Tug it out, replace it, and you're done. Screw the two panels back on, and you're on your way. Ask at the automotive store for the Signal Flasher Relay... they'll know what you need.