Vista - ASP.NET Password reset

Several weeks ago, at someones suggestion, I changed my Administrators
Account to a Standard User Account.This was as a result of the topic "Why use
a standard user account instead of an administrators account. I must have
changed something as a result. I'm regretting this. Now, when I want to
make any changes a window appears, Asp.net Machine Account, and asks for a
Password. I never set up this account and do not have a password. When I
check my user accounts all that is shown is a Standard Account. The
Administrators Account is no longer listed. I was told this Asp Account is
blocking my Administrators Account. My Administrators Account was set up
without any password.

Is there a remedy without reinstalling Vista?
I can not download anything to fix problem because I can only use the user account I cannot change to Admin account the ASP.NET password box comes up and the password that I put in and confirmed the password it doesn't work what do you suggest I do if you can not down load anything to fix the problem?