Hidden Admininstrator Account?

Doesn’t Windows XP “hide” an administrator account? I have a friend that asked my help with something I’ve never run across, but I would love to learn the solution anyway.
She said a friend was “fooling around” on her computer and somehow changed her primary account (it’s the only one that the computer powers up to)to need a password, but in doing so also changed it to a limited account accidentally. Now she can’t make any changes including reset the access. There are critical updates that she can’t even download.
She said when she clicks on the user account, there is NO option to change the access, only the picture.
Can she access an administrator account to correct this or does she have to reinstall?
Thanks in advance,
Kathy