Did you solve this problem. I have the same problem.
I have an Arduino Uno.
Arduino is not showing up in device manager (not in ports or as an unknown device).
The light is coming on and it looks like it came loaded with the blink program because it is blinking.
I tried changing the USB cable. Nothing.
I tried changing the PC 3 times. First with the IDE installed on my windows 10 computer.
Second time on my windows 7 computer without IDE installed.
3rd time on a MacBook.
Everytime it was the same. Lights come on, on the board but nothing is registered on the computer.
Any ideas?