The easiest way is, create a text file (or) Notepad and write "COMMAND" in it and then saving it as "cmd.bat". This will give you access to Command Prompt by a double click.
If this doesn't work at all or you need to allow the use of REGEDIT and CMD you can just make your own registry file and run it on the computer. This will give you the rights to use them. Simply write the below lines in a text file (or) Notepad.REGEDIT4 [HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesWinOldApp] "Disabled"=dword:0 [HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesSystem] "DisableRegistryTools"=dword:0
Save it as test.reg and run the file. If it prompt a Yes or No message then simply press Yes.
After that you should have access to Registry Editor and the Command Prompt.