Change Your Windows Password When You Cannot Login
You need to login to Windows, but you forgot it and tried every password you know, follow the simple steps below
Get and burn a copy of the System Rescue CD using another computer. It includes the tools required to get your computer back on the road.
Boot from the System Rescue CD and wait. It takes a while to start. You should be booted into a prompt. Don't be scared yet - even if this is not graphical.
Mount your Windows partition, which means you'll need to find your Windows partition (try ls /dev/*d* and only use the devices ending in a number) and mount it using ntfs-3g (device) /mnt/windows -o force and press enter.
Go to the config folder inside your System32/System64 folder. Most people will type cd /mnt/windows/Windows/System32/config and press enter.
Type chntpw -l SAM and press enter. This will list the accounts on your computer.
Type chntpw -u (username) SAM and press enter. Pick 2, unless you use the latest Windows version, then try 1 (either option, press enter). If picking 2, enter the new password. Either option, say y to the next question.
Type reboot and press enter. Take out the SystemRescueCd.
You should now be able to log in.
Some computers have an "recovery" partition. Be wary of the partition you mount.