Try using the run command on the start menu or through the task manager.
type CMD.exe and hit run or push enter
Also,
As said above, open a notepad file
type
save as anything ending in .bat
I have a few more but i gotta do something.. Ill post later
EDITT::: okay, the next option depends on how much access you have to the system, and if the prompt was turned off in this way..
If possible, Try to get to your Local Group Policy editor.
On the left side click on User Configuration, Administrative Templates, and System. Now in the box on the right, You should see a list of objects and one of them says "prevent access to the command prompt." Double click that and it should open a dialog box where on the top, it should give you 3 bulleted options, "enabled" "disabled" and "not configured." Select Disabled or Not configured and press okay..
Another option is through Registry editing.
Open REGEDIT (if you can)
If prompted, select Continue
Now, in the left pane, Navigate to "HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\System"
After opening the system folder, Look in the right pane of the window
right click on DisableCMD and click on Delete
Click yes and confirm the deletion
Close REGEDIT
That's all I have for now. I don't really know much about Vista so this is all the help I can offer
