Arduino UNO R3-PC communication error
Purchased Arduino UNO R3 last week. I completed the installation steps per Arduino website and ran the "Blink" code with the LED attached to pin 13. Following this, I tried using the Adafruit Motor Shield to control a 12V, DC Stepper. The code was taken directly pasted from Ladyada website <<http://www.ladyada.net/make/mshield/use.html>> with minor tweaks, i.e steps and stepper#. But I could not upload the code on to the arduino and the "Serial Port" selection in "Tools" was grayed out. Now when I connect my Arduino via USB, I cannot establish the COM3 virtual port, initially designated for the microcontroller. Furthermore, Arduino "ON" LED does illuminate but I think I am running an infinite loop of the "Blink" code. This is what I have tried so far:
1. Resetting the board manually. No impact.
2. Changing USB cables. No impact.
3. Verifying the UBS ports function. Yes they do.
4. Used Arduino with another pc. Still the same results.
5. Reloading and running the installation process of the board. But my pc does not recognize the board anymore and the board just keeps on running the "Blink" code. Also, the device manager does not recognize any UBS connection or the Arduino COM port.
Are there any more variations I can perform that either may help me understand the errors or fix this problem? Also please let me know if you need more information regarding my setup.