If you have completely forgotten your password then it is not possible to get it back. In such case you can use Windows password recovery software to reset your password. There are many Windows password recovery software available so you can use any of them which is compatible with your PC configuration.
Well, there would be some doubts about telling you the recovery method as nobody knows who the real owner of the computer is. However, you can use password recovery tools to recover the forgotten password.
firstly, try to write some clues that may remind you of the password, and type it to see if it is the right password, if it still does not work, you could try some professional windows password reset software, like Pwdspy Windows Password Recovery