And recently just found out a very very useful Window XP Hacking tools that may help you to overcome this problem.
This is the solution:
1. Restart your computer and keep pressing F8.
2. From the menu, select to boot in save mode with command prompt.
3. once you’re at the command prompt, type “net users” (without quotes)
4. You will see a list of usernames. Pick the username that you are using and type “net users username *” (without quotes, replace username with a real username from that username list)
5. You will be asked to enter a new password and a second reconfirmation.
6. Press enter and you will be told that your username password has been changed successfully.
*Hope this will help