You are locked out of your system because you forgot Windows XP password, it happens to most of us in nowadays, so there is no need to worry about. Here are some tips you could follow

Use Windows XP password reset disk

If you are lucky to have created XP password reset disk in the past, insert the disk to your locked computer, when at the login screen, reset the password to a new one.

But the disk only works in a certain account you’ve created for, if you changed the Windows XP password for that account, it still works.

Use PC Login Now

PC Login Now is one of the better free Windows Password Recovery programs I’ve tested. Instead of finding out your current account password, PC Login Now just deletes or removes it, allowing you to access XP without a password. It ‘ s much easier to use the program, you can find details from the official website, but the only disadvantage is that PC Login Now only remove less than 15 character password.

Have another Administrator change your Windows XP password for you

If there are other people that have accounts on your computer, check if one of them setup with administrator rights. These kinds of account would be able to reset your Windows XP password for you, just log in that account and go to Control Panel to find out the password reset interface, click that locked account to change a new password.

Hack your account password with Windows Password Key Enterprise

If you’ve tried all of the above tips and no one can help, then It's time to try something more complicated.

Windows Password Key Enterprise is designed to reset or delete your Windows XP password by making some kind of boot disc. It comes as an ISO image file for which you use image burning to make a bootable disc. I’ve tested it and it’s 100% recovery rate. The process can be done as following:

Log in any other available computer but remember not your locked one. Download Windows Password Key Enterprise and Install it, then burn the ISO image file to a blank CD or USB flash drive.

Insert the newly created disk to your locked computer; make your Windows XP boot from this disk, usually by changing the BIOS setup. Then the program will works and auto reset your locked account password to a blank one.

When forgot Windows XP password, a clean install system isn't a smart choice, it is drastic and obviously destructive. Follow the above tips, I am sure you could regain access to your account soon.

Source: http://www.lostwindowspassword.com/forgot-windows-xp-password.html