Easy Steps To Change Administrator Password in Windows XP
First open CMD. (start > run > cmd)
type net user , hit enter
Then the computer will show you list of users.
As a example you want to change the password of user; manoj
Type net user manoj * , and hit enter
Then type a password. Then verify that password.
Thats all........So in this way you can change the password of any account without knowing the old password.