A few areas you might want to look into, listed probably in the order you want to check.
1) Did the "wire slipped off" cause a short or merely cut power abruptly? You probably would want to check to make sure other components are not fried or anything.
2) Check the USB hub. How are other USB devices doing? Try pulling out the touch screen usb cable and plugging into another port? Does the OS see the touchscreen plugged in?
3) Try reinstalling the Touchkit program.
4) Bust out a multimeter and check to see if the touch controller is powered and all that good stuff.
There probably are other stuff to check, but it's 3am and my brain is already asleep.