How to restore the Administrator account in Vista

You can enable the built-in Administrator account if you really want to, by running the Command Prompt as administrator (right click its icon and select Run as Administrator; click Continue at the UAC prompt) and typing the following:

net user administrator /active:yes

This causes the Administrator account to appear on the Welcome screen. Note that it does not have a password set by default; the first thing you should do is set a strong password for it.