Password

Installed XP yesterday, I have only set up an
administration user (default). Set password to log on as
administrator. I went on line and downloaded the latest
critical updates (about 23 of them). After reboot, my
password will not work. I did find the 2000 look a like
screen but it would not work there either. How do I fix?
Would I need to call Microsoft to unlock it? I did
register it on line after instillation. Thank you for
your help in advance.
JR