Alright, sometimes this can happen. Mainly because people that want to steal your personal items; however, they can disable command prompt by the registry, and you will not be able to use it. Here Is a way you can connect to it, If it still says Access Denied you will have to go to safe mode under your Administrator.
Here we go.
One way.
Step 1. Click on your Start Menu-All Programs-Accessories-NotePad.
Step 2. Once you opened NotePad, type
cmd.exe
Step 3. Then click File-Save As. Click on your Desktop(so the file will save on your Desktop.)
Step 4. Save it as cmd.bat.
Step 5. Go to your Desktop and double click cmd.bat and it should open.
Another Way.
Step 1. Open up NotePad again.
Step 2. Type command.com when your allowed to.
Step 3. Save to your desktop as Command.bat.
Step 4. Go to your Desktop, and double click Command.bat.
These should work, if you have any problems post here and I'll try to help.