This hack will allow you to change the password of any computer from a boot disk.

Burn the .ISO file to a CD.
Get out the newly created CD and insert it to the locked computer.
Reboot the locked computer and then follow the process of instructions. Just a few steps and the old password will be removed.

Setting up new password:
Step one: Open the “Control Panel”
Step two: Click the “User Account ”
Step three: Select the account you want to set a new password.
Step four: Click “changing Account ” and “set up password”, then fill out the form as listed. Click “Create Password”.