If you are unable to Administer a Windows Users password on a computer you may need to modify the way Windows normally functions in order to bypass this issue.
Using a Linux Boot CD, on the hard drive where the Windows operating system is installed.
cd /Windows/System32/
mv Ultilman.exe Utilman.exe.bak
cp cmd.exe Utilman.exe
So by switching Utilman.exe to be the cmd.exe program, we can get a command prompt when you click on the accessibility button on the log in screen.
Boot the computer into Windows. When you get to the log in screen click on the accessibility button, you will get the Windows command prompt.
In the Windows command prompt run the command:
net user Username password
To change a Windows User’s password using the command line, you must set the password to something, it cannot be left blank. So you could set the password to “password” if you like.
In the case that its Windows 8 and it is a Microsoft account, you cannot reset the password like the previous example, however you can use this command on the command prompt:
net user Administrator /active:yes
net user Administrator password
Then reboot the computer and log in to the new administrator account. Change the Windows User’s account to local, then set/unset the password.
This activates an Administrator account so you can go in and manually administer the users password through windows.