There are many ways to open command prompt and other files if you do not have the access priveleges to do so. One easy way to do it is by creating a simple .bat file, storing it on a flash drive, then using it to open any file you might want.

All you need to put in your .bat file is:
@echo off
command.com

The .bat file above will open command prompt for you, bypassing any access restrictions. In most cases this technique will work.

Here's a quick video I found on youtube on how to do it.