Why is the ford focus information display not working?

It depends on what You mean about it not working: If it's not responding to Your touch, but You can see items on it, or if it's purely black. I'll assume the latter. A fuse is an obvious problem here; check the relay first, in the fuse panel below the dash on the driver's side. If that's all good, then it's possible there's a malfunction with the infotainment unit itself. To try to reset it, hold down the Seek Up and Audio Power buttons on the unit for approximately 5 seconds. If this works, You should see a blank screen followed by the Ford splash screen. The next thing You can try is resetting the entire electrical system; remove the negative cable off Your battery, and turn on the headlights for a few minutes. Then, wait about 15 minutes for residual system memory to fade and rehook up the battery. If this doesn't fly, You should start suspecting the infotainment unit itself needs replacing.