First, Log in and go to your DOS command prompt ( Start > Run > Type in Cmd > Enter ) and enter these commands exactly:

Method #1 ( Not working in SP2 )

mkdir adminxp
copy logon.scr adminxp\logon.scr
copy cmd.exe adminxp\cmd.exe
del logon.scr
rename cmd.exe logon.scr

So what you just told windows to backup is the command program and the screen saver file. Then you edited the settings so when windows loads the screen saver, you will get an unprotected dos prompt without logging in. When this appears enter this command that’s in parenthesis (net user password). So if the admin user name is Admin and you want the password password123 then you would enter “net user Admin password123″ and now you’ve changed the admin password to password123. Log in, do what you want to do, copy the contents of temphack back into system32 to cover your tracks.

or you could use this way to gain administrator access on a local machine.

Method #2 ( Not working in SP2 )

net user tempadmin tempadminname /add
net localgroup Administrators tempadmin /add

*This is just administrator level on a local machine not in a domain.

Method #3 ( Working in SP2 )

What you need is just a windows XP installation CD:

  1. Insert the Windows XP CD and restart your PC.
  2. While the CD is boot, you may see “Press any key to boot from cd”, hit it.
  3. Just like normally windows installation and while you at Welcome to Setup screen, press ENTER to Setup Windows now.
  4. Press F8 to accept the Licensing Agreement.
  5. Setup screen will appear and this will show “If one of the following Windows XP installations is damaged, Setup can try to repair it” . You need to press R to begin the Repair process.
  6. Let the repair run until it reboot, after reboot will be start Installing Windows.
  7. At this stage is the most important part, while the lower left hand side of the screen display Installing Devices progress bar, press SHIFT + F10. This step is the security hole and it will prompt you a command console.
  8. At this DOS prompt, type NUSRMGR.CPL and enter. you will gain a graphical access to your User Accounts same as your control panel
  9. At this stage, you may change the password you prefer or remove the password
  10. If you want to login windows without asking any password, type control userpasswords2 in the command prompt.
  11. After made the changes, close the windows, close the command prompt and continue windows repair. After repair done, you will have your new password to login windows, all the setting in there are still remain same.

This method without need to buy any special tools or software, we just use the security loop hole to crack down the password, but the disadvantage are time consuming. T

*Notice: I am not responsible on what you do by using this trick to gain admin rights.

** Method #1 will reset the admin’s password to your changed password and there is no way this could be reversed. Beware of this point.

*** Tested on Windows XP Professional and Windows XP Professional SP2

credit to : Method #3