The path may be unknown or too long. This tutorial demonstrates how to open a command prompt window at any location in Windows 7.
Go to the location where you want to open the command prompt window. (e.g. the Desktop)
Press the Shift key and right-click simultaneously. This menu has the option “Open command window here”. Click on it and you are good to go..
The same thing can be done when right-clicking on a folder also.