Only Account is the Guest Account

Hi,
Initially, I've had my only administrator account. The problem was the system was not able to login automatically which has no password (pwned). So, i went through here Log On Automatically at Startup.
But the problem was I accidentally removed the Administrator Group from my only account, whether you believe it or not - It accepted and went on. I logged out and logged in to find that my current account has been turned into Guest account and don't have the administrator account.

Now, this is the problem I've run into : I am not currently in Administrators account and I cannot make changes to account/install a software.

I've tried out the cmd.exe with creating administrator using netuser and it showed System Error 5. Access Denied. Mostly I get an Access Denied error on all occasions.

I'm not able to create password for Administrator account which is disabled too!

P.S : I have a dual boot system with Linux as an another OS. So, creating folders in the partition is not a problem.

Reboot the computer, tap F8 repeatedly to access Safe Mode, see if Administrator is listed, boot in to create a new User Account with Admin privileges.

If this fails see if Repair console is on the Advanced Boot Options, boot in, choose Admin account if given, create new Admin account in User Accounts.

If this fails boot into Win7 DVD Repair console or Repair CD, press Shift + f10 at boot or click through to Recovery Tools list to open a Command Line, type net user administrator /active:yes

reboot into built-in Admin account to set up a new Admin-level account in User Accounts.

Thanks for instant reply.
That helped.

If you used the hidden Administrator to establish a new account, I would hide it again now by opening a Elevated Command Prompt to type net user administrator /active:yes