Note: This trick works only if the computer is turned on and then you can change the password.
Step 1: Click on start and then search for cmd (i.e., command prompt).
Step 2: Right click and then click on Run as administrator. It will prompt for request to proceed. Click on OK and then the command window will open.
Step 3: Type net user. This command is used to find the name of all the user account present in the computer.
Step 4: Change the password of all the user account one by one by typing.
net user useraccount password
Here useraccount is the account which you got from the step 3 and in place of password type your desired password.
With these simple steps you can change your Windows password or even of yours friends.