try this: http://www.loginrecovery.com/

try searching the web for third party software that offers to recover lost password in xp..there's no easy way to recover lost password..or try using other log in name such as Power Users.. Backup Operators..maybe the account is turned on...

If you didn't set administrator password , press ctrl+alt+del on welcome screen then type administrator in user name filed and press enter.
but if you set admin password, use bootable disk to remove your password.

Easy way:


as soon as the pc switches on tap F8 repeatedly. A menu will come up - choose "Safe Mode" and then wait a while. Lots of text will come down the screen and the graphics will look crappy but dont worry. There will be a user called "Administrator" shown on the welcome screen in this mode. Log in as it (no password) and then delete the password on your usual user account

help want to log to XP prof, but dont have username or password

As jb posted above, if the Administrator ac has no password, then you are in..
I do hope you have permission to be using that computer. Do not know the username?!

Yes I do have permission. Its my boss laptop and he has asked me to fix it for him.
What if the administrator username was changed

not likely

Or, to expand a little on sittas's post... the Administratot remains the Administrator - this is the base admin account; I don't think it is possible to change the name from Administrator. Other admin acs are initially clones of this one.