Not sure if I'm reading this right but can't you just start in Safe Mode and log in as admin, because windows has a "hidden Admin Acct." or Safe Mode with command prompt and activate the "hidden Admin Acct." by using " net user administrator /active:yes " or
If you have a Windows 7 installation DVD (not a recovery DVD) you can boot the system with it. Select the default language, then choose "Repair your computer". Then select "Command Prompt". At the command prompt type:
net user administrator /active:yes [enter]
Remove the DVD, reboot the computer, and log into the built-in Administrator account.
Also check Here Built-in Administrator Account - Enable or Disable