Windows password cracking

Before beginning you should know what is hash and how and where the passwords are stored as hash in windows.
For cracking windows password using Backtrack you should have a Backtrack cd. Insert cd boot to cd. Now Backtrack have many offline password cracking tools pre-installed, we will use one of them.
From tool we have to create a directory to which we have to mount the SAM file that is in system32/config.

Continue using following steps:

step 1 open applications>Bactrack>Privilege Escalation>Password Hacks>Offline Attacks>chntpw

step 2 type fdisk -l

step 3 type mkdir /mnt/apple

step 4 type mount -t ntfs-3g /dev/sda1 /mnt/apple

step 5 type ./chntpw -l /mnt/apple/WINDOWS/system32/config/SAM

step 6 type ./chntpw /mnt/apple/WINDOWS/system32/config/SAM

step 7 after you have the user edit menu select the appropriate step, here we have to clear password so type 1 and press enter

step 8 now it will ask for writing hive files so type y and press enter

Now your windows password has been cleared. When the next time you will login it will not ask for password.