There are also two tips for you.
The first one is a bit complicated,if you are proficient in Computer,you can have a try.Windows XP' password stored in Windows \ System32 \ Config under the SAM file.Ok,the you may know how to do.
Step 1:Login to a Computer that has Windows XP system.
Step 2:Copy the SAM file to a floppy disk.
Step 3: Then turn to your locked pc and insert the floppy disk Reboot the PC and enter into MS-DOS.
Step 4:In dos,type : del c: windows\system32\config\sam ,then you will delete the SAM file.
Step 5: type : Copy a:\sam c:\ windows\system32\config,copy the other's SAM file to your PC.
The second one is very easy,everyone can understand how to use.What is more,this can 100% help you fully remove the unknown password
Simply go to Windows Password Key website http://www.lostwindowspassword.com
to download this tool,it is a power windows password recovery software And most of all, it's the most popular and safe solution for resetting your Windows password until now.
Step 1.You need to login a pc which can link to internet and download the software
Step 2.Prepare a blank CD/DVD or USB flash drive,and intall the program to that pc
Step 3.Run the program and burn to CD/DVD OR USB flash drive
Step 4.Turn to your locked PC,insert the newly create CD or USB to your drive.Reboot the Computer and then follow the instructions,it is very easy to use.