windows 7 - Administrator account disabled, can't boot into safe mode

I recently obtained a used windows 7 computer. The only visible user had administrator privileges, and its name was that of the previous owner's. I changed the name via User Accounts ► Change your account name, but for some reason that revoked my admin privs. Now, whenever I try to do something that requires admin privs a box pops up that wants me to enter an administrator password, but doesn't have any place to type any password.

After a bit of googling, I found a few places that said the first step to fixing this was to boot into safe mode. I restarted the computer and pressed F8, but that didn't do anything. The only other way I saw to boot into safe mode uses msconfig, which needs admin privs. I tried changing the name back, in case that helped, but that, too, requires admin privs.

How can I get my Administrator privileges back?

Answer

I have two answers for you.

The first is not a solution to your immediate problem but still... Reinstall the system.

Sure, I might be a bit over obsessive about safety, but for me that's quite a risk to run a system somebody else configured. It just has security risk written all over it. :P

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The second solution is actually an answer to the problem - how to get admin privileges on a Windows machine you have physical access to.

• boot the machine into live linux distribution - Debian/Ubuntu/etc


• mount the windows system partition


• cd into mounted-partition/Windows/System32 and backup osk.exe, that's On Screen Keyboard executable. After doing that, replace it with cmd.exe - like cp -f ./cmd.exe ./osk.exe


• reboot into Windows, on the login screen click on the Ease of Access icon on the left bottom, and choose the On Screen Keyboard. This will run cmd.exe


• in the console window type: net user user_name new_password to reset admin account password. You can then log into that account and do whatever you please.


• of course you need to undo the changes you've made. ;)