Windows 7 - Administrator Privileges To Deny For All

While attempting to set up a new computer on our network I seem to have lost access to many documents and lost permission to many folders. While setting up a new computer we began playing with what programs and documents the new computer could access. (The new machine is to be used for clients, and for internet/printing privileges) we did not want the computer to access anything on the network except the printer.

We did the above by right clicking on the public folders where we kept our documents, opening the security tab and restricting the permissions. We would then deny the new computer access via the ownership tab. This seemed to work as the new computer on the network had no access to our files but could still print to the printer on the shared network. I wasn't on the computer at the time, (my lackey status didn't permit as such) and I think somehow the other person managed remove our access to the programs/documents.

I think they did this by changing the admin privileges to deny for all. I am guessing that's what happened because now when I try and take ownership of the files I am unable to open them. It will let me take ownership of the files but then still says me access is denied when I try to open any of the selected files of documents. (does not prompt for password). In short, Is there a way to reestablish my admin privileges after what appears to be simple mistake on which account was selected?