“How to recover lost administrator password”

Set your Hard drive to another PC and install the second copy of operating system.

That way is to try to reset the administrator password to something you do know and allow you to access to the user profile and the data. In most cases, this is the best solution. However, If the data is encrypted using the Windows XP Encrypting File System (EFS) or other encryption, you probably will not be able to gain access to those encrypted files by changing the administrator password. 

I also searched and found a tool that can reset administrator password this is Petter Nordahl-Hagen’s Offline NT Password & Registry Editor This is absolutely one of the best free tools to reset the administrator password and gain access that I have ever used. It modifies the encrypted password in the registry’s SAM file allowing you access to the account in Windows NT/2000/XP/2003/Vista systems. 

They also provide a bootable CD and floppy images to be able to modify the administrator password and access NTFS partitions. You do not need to know the old password to set a new one. They have a very helpful feature that can detect and offer to unlock disabled or locked user accounts. The program also supports Windows Vista.