Enable the Administrator Account in Vista

1. Open the command prompt with Administrative privileges by opening the Start Menu, and typing cmd in the search box, and then press Ctrl+Shift+Enter or click the Start orb, All Programs, Accessories, right-click Command Prompt and select Run as administrator.
2. Type the following in the command prompt and press Enter after:

net user administrator /active:yes

3. Restart your computer and logon as Administrator.