Spyware on computer changed admin account to restricted account, need help

I allowed a friend visiting from out of town to use my computer, he proceeded to download some files which ended up containing spyware. My computer only has ONE user, my account which is the admin account. The spyware has apparently changed the admin user to a restricted user account, and I can no longer access control panel or other parts of my computer on it, as it says it is restricted and I do not have admin access. My user account is passworded and I have not forgotten the password. It is treating my admin account as if it is a normal user account, Is there any way I can fix this? I have ran 3 different spyware/ virus scanning programs and removed or quarantined everything it has found. Any help would be greatly appreciated.