All you need is Password Recovery Bundle, a Windows password cracker tool. Borrow someone PC, download the tool and create a password reset CD. Then boot your PC with the CD and perform password cracking. But make sure to set your BIOS to boot from CD or you will end up with boot into Windows 7 logon screen.  Follow the step-by-step instructions to crack Windows 7 password:

1. Before the work, prepare a blank CD/DVD.  Then install and run Password Recovery Bundle on your computer.  Click Windows Password button to bring up the CD recording dialog, burn the default ISO image onto your CD.  The CD is the Windows password reset CD we’ll later use to crack Windows password.
2. Insert the Windows password reset CD into your locked computer. Set the computer to boot from the CD.
3. Restart the computer, it will start to boot from the CD.  After a while, your computer will launch the Reset Windows Password program. The software automatically detects your Windows 7 SAM registry hive and show a list of user accounts existing in your Windows 7 system.
   
4. Choose the user account whose password you already forgot, then click Reset Password button to remove the password.
5. Remove the CD and restart your computer.

“How to crack Windows 7 password in a short time?” You’ve done it now! You’ll find you can get into the computer directly without being asked for password. Not only for Windows 7, the Windows password reset CD you’ve created can also be used to crack Windows password on Windows Server 2008/2003/2000 and Windows 8/Vista/XP/Me.

Note:  Ophcrack is only intended for computer geek, not ordinary, nontechnical folk. For average computer users, the most efficient and easiest way is to use Reset Windows Password utility.

Ophcrack is a free (open source) Windows password cracker/recovery tool based on rainbow tables. It is a very efficient implementation of rainbow tables done by the inventors of the method. It comes with a Graphical User Interface and could be used to recover Windows 7/Vista/XP password.

How to Recover Windows 7 Password Using Ophcrack?

1. Download the Ophcrack from the official website. When you go to Ophcrack download page you will notice there are LiveCD ISO’s for Windows 7 and Windows XP. Based on the operating system of your locked computer download the ISO for that operating system (Windows 7 or XP). It won’t hurt to download both because you never know when you might need them.
2. Burn the ISO image on to a CD. It will create a bootable CD for you. I use BurnCDCC for this. You can use anything you like.
3. Now put the CD into the CD-ROM and make sure you set CD/DVD as the first boot device inside the computer BIOS.
4. When it boots from the CD, you will see the list of the accounts on the computer.
5. The machine will do its thing and just leave it. After a while, you will see password has been recovered and displayed on the screen beside the accounts those are not password-protected.
6. After you see it – remember it just reboot the machine and you should be able to log on to Windows 7 system.