Its happen with all of us, we are in hurry and we mix our windows password with other one or we forgot
windows password. And most people format computer if they forgot there login password. but here is the way to reset your password ...
you just need bootable CD/DVD of your windows
Windows XP
1 ) Place your Windows XP bootable CD in your cd drive and re-start your system
2 ) Keep eyes on screen when you see booting message "Press any key to boot from cd", Press "Enter"
3 ) Setup will start Loading system and other files, wait till you have "Welcome to Setup" screen
4 ) Press enter to start setup, on "Licensing Agreement" Press "F8" to accept it and continue
5 ) Now you will get "Setup" screen, here you will see Repair and Install Windows option, press "R" to select repair option
you will see something like this on screen, “If one of the following Windows XP installations is damaged, Setup can try to repair it”
6 ) Wait and all Repair run, its check your disks and then start copying files for several minutes
7 ) Setup will be required to Reboot/Restart, your system will reboot it's self
8 ) While reboot don't press any key, till "Installing Windows" screen open
Normally when you enter a username and password... Firefox will ask if you want Firefox to remember them, with "Remember", "Naver for This Site" and "Not Now" options. but hacker found a some trick by adding a small script there, if you are useing any public computer at office or cafe or any other place be careful if firefox on that computer hacked, its save your Username and Password silently without your permission even you click on "Naver for This Site" or "Not Now"।so if you are useing firefox on public computer just check if your Username and Password auto saved or not before left that computer.
Check and Delete if Username and Password if auto saved:
1 ) In Firefox open "Tools" menu and click on "Options".
2 ) Click the "Security Icon" from toolbar.
3 ) Click "Saved Passwords..." button, and the Password Manager will open.
4 ) You can see Particular website name and Username list there.
5 ) To be extra sure it's your id, Click on "Show Password" button.
5 ) If your ID and Password there in list, select them by click on it.
6 ) Click on "Remove" buttion to delete them.