Note. You need windows XP, i don't know if it would work on vista.
ask the admin to unblock it, if you want to get in and change his/her password (and you know they'll allow it), make sure you have windows XP.
Method 1.
1. Get physical access to the machine. Remember that it must have a CD or DVD drive.
2. Download DreamPackPL from the sources.
3. Unzip the downloaded dpl.zip and you’ll get dpl.ISO.
4. Use any burning program that can burn ISO images.
5. After you have the disk, boot from the CD or DVD drive. You will see Windows 2000 Setup and it will load some files.
6. Press “R” to install DreamPackPL.
7. Press “C” to install DreamPackPL by using the recovery console.
8. Select the Windows installation that is currently on the computer (Normally is “1″ if you only have one Windows installed)
9. Backup your original sfcfiles.dll by typing:
“ren C:\Windows\System32\sfcfiles.dll sfcfiles.lld” (without quotes)
10. Copy the hacked file from CD to system32 folder. Type:
“copy D:\i386\pinball.ex_ C:\Windows\System32\sfcfiles.dll” (without quotes and assuming your CD drive is D:)
11. Type “exit”, take out disk and reboot.
12. In the password field, type “dreamon” (without quotes) and DreamPack menu will appear.
13. Click the top graphic on the DreamPack menu and you will get a menu popup.
Hack Windows Login Dreamon
14. Go to commands and enable the options and enable the god command.
Bypass and hack user account passwords
15. Type “god” in the password field to get in Windows.
You can also go to Passwords and select “Logon with wrong password and hash”. This option allows you to login with ANY password.
Note: I was unable to bring up the DreamPackPL for the first time because I have Kaspersky Anti-Virus already running in background. I believe most antivirus already labelled this tool as a Hack-Tool. A Hack-Tool is NOT a virus. DreamPackPL helps you bypass the Windows Login screen and it is not destructive.
Method 2.
1.Click Start then go to run
2.Type CMD and it will bring up command prompt
3.Type Net user, it will come up with a list of all the users on the computer.
4.Now write net user [Name of user] *(dont write name of user use the actual username) and press enter.
5.type in a password twice and it should change it.
Thats how it worked on mine.
Hope is was helpful.