Unlock computer

how do I unlock my computer if I forgot the password and only the admin account

Boot into Safe Mode by pressing F8 repeatedly as soon as the computer starts then log into the Administrator user and change it password

When you open your computer it says enter your username and password, change the username to administrator and log in to this computer in the last box then click enter, after that go to user account and select your old account, in the bottom of the box you will see it says reset password type your new password.