There are several ways to recover if you did not create a password reset
disk when you set the password on that admin account.
1. If you have a retail Vista installation disk, you can use the procedure
from the following website. Use the Option 2 there.
What do I do: I can no longer log in or elevate to an administrator account:
http://www.jimmah.com/vista/Administration/locked_out_of_admin.aspx
If you do not have an installation disk, there are free password recovery
procedures on the internet, I usually do not recommend these simply because
they require advanced computer skills and some of them can turn your
computer into an expensive doorstop.
As a last resort, there is software available that you can purchase that
will solve the problem, easily.
The program that I recommend is the first one, it is very easy to create a
recovery disk that you can use on any Windows PC. These recovery programs
usually cost about 30-40 USD.
A@PC: Windows Password Recovery Software. Reset Administrator Password. XP
VISTA 2003 2000 NT.:
http://www.password-changer.com/
Windows Password Recovery Key - Resets the Administrator account password:
http://tinyurl.com/2qr7oc