What should your do when you forgot the password to login to windows system? Ask an administrator to reset the log on password for you. If you yourself are administrator, and you can't remember the administrator password, the problem get a little tricky, and probably hard to recover the "forgotten password" again. Before you search for recovery CD or Windows DVD to format and reinstall Windows onto the computer, here a few solutions you can try to unlock the windows to gain access to the system again, at least by resetting the password
Method 1: Take a rest, and try hard to remember the forgotten password
Sometimes, human being is a little weird. You won’t get the thing that you urgently need. So have a coffee, take a snap or even come back after a few days, you may found that you suddenly ‘remember’ your Windows password.
Method 2: Try No Password Administrator Login Backdoor
In Windows XP (not Windows Vista as Administrator account is not enabled by default), there is built-in Administrator user account, that has administrative credentials, enabled by default, and without any password to protect the account from been access. If you didn’t change this Administrator’s password, then try to sign in to Windows XP without password.
Method 3: Reset password from another user account with administrator credentials
If you cannot log on to Windows by using a particular user account, but you can log on to another account that has administrative credentials, follow these steps on how to do the trick: Log on to Windows by using an administrator account that has a password that you remember. You may need to start WinXP in safe mode. Click Start, and then click Run. In the Open box, type “control userpasswords2″, and then click OK. Click the user account that you forgot the password for, and then click Reset Password. Type a new password in both the New password and the Confirm new password boxes, and then click OK.
Method 4: Do-It-Yourself (DIY) third party recovery tool
There are a lot of tools and utilities that can be downloaded and used to recover, reset, retrieve or reveal existing password. Take Windows Password Unlcoker for example, Windows Password Unlcoker creates a password reset CD that work during the boot process and instantly reset Administrator or other account passwords and Windows security setting which prevent you from logging in.
1. Download a reliable third part utility (here, take Windows Password Unlocker 4.0 for example) and save it to your hard disk. Take note of what folder you saved the file in
2. Burn the downloaded ISO file onto a CD. * To burn your CD, you'll need a blank CD-R . * If you are familiar with burning .iso image files you may use any software you already have such as Nero, Sonic, Roxio etc. If you need burning software we provide one of the best solutions on the market called BurnCDCC.Put in your newly created CD and remove your Windows password.
3. Insert newly created CD in your CD drive and reboot your computer. When the CD boots, you'll see Windows Password Unlocker 4.0 initializing (see screen shot below). If so, you can continue to the next step. If the computer still boots into Windows, it's necessary to change BIOS boot sequence to make it boot from the CD

4. Select the user account you want to reset

5. Click the 'Reset' button to process.

6. Click 'Yes' to confirm your action. Or, click 'No' to undo your selection.

7. In the end, a message box appears as below, indicating Windows Password Unlocker has successfully reset the password