dmjlambert:
While the Uno is connected to the computer with the USB cable, put the ATmega16U2 USB-to-serial chip into DFU mode by resetting it. Reset it by carefully and briefly shorting the leftmost 2 pins on the ICSP header next to the USB port. See if you get a device show up in device manager then.
I tried what you suggested but the board didn't show up. It didn't seem to respond at all, the L LED continued to repeatedly blink with out a pause. Thanks for the suggestion though