Virus takes over admin?

Ok, so I accidently downloaded a stupid hack file. When I ran it, the computer shut down and rebooted and when it came back on, it took over administration controls. This is the only user on the account and it IS the administrator. So, internet is running fine(with google chrome) and everything else works. The things that i can't get access to is changing anything in the hard drive. This also includes not having access to the command prompt, task manager, control panel, and system restore. These things do not work, even on safe mode. I have ran security scans on both mcafee and vipre. I would download norton trial, since its the best antivirus out there, but its really too much of a hassle. Is there anyway i can search up the virus and delete it? I have windows seven, and no, i do not have the windows cd, so don't even mention redownloading windows. Please help! Thank you!