Change Window 7 Password Without Knowing Current Password

Step 1:
 Click on Start type Run and Hit enter. Or Simply press windows key+R.
And type this comment in Run Box

compmgmt.msc

Step 2 :

Computer Management windows will open, Select System Tools from right window pane.

Step 3 :

Under this, just double click on Local Users and Groups and then click on Users.

Step 4 :

Now you will see all the login accounts of your computer.

Step 5:

Right click on any, the account whose password you want to change and then click on Set Password.

Step 6 :
A warning message will popup on your screen just click on Proceed button.

Step 7 :

Now enter your New Password and click on OK button.