Assuming that your PC runs on win 7,you can recover your password in some ways below:
Solution 1: Reinstall Your Windows 7 Operating System
The most primitive method is to reinstall your Windows 7 operating system. If there is no important file in your C disk and you have no idea about how to get the lost password back or reset it, you can use this method.
Solution 2: Unlock Windows 7 Admin Password from Safe Mode
Windows 7 system has a built-in administrator account that is created during Windows installation and disable by default, which has no password in it. You need to enable that account before forgetting your other admin account password. Otherwise your built-in administrator account won’t appear in the screen in this tip.
Step1: Start your win 7 computer and press “F8″ while the computer boots up. Scroll down to “Safe Mode with Command Prompt” with the arrow keys on the keyboard and press “Enter.” Your computer starts in Safe Mode with Command Prompt.
Step2: Select the Administrator account that appear in the screen, then enter command prompt. Type: net user ****** 123456 and enter (****** is the account name and 123456 is the new password), it will show you a message that” the command completed successfully.
Step3: Restart your win 7 computer, then you can log in as ****** with the password 123456. You can go to control Panel to change your account password if necessary.
Solution 3: Unlock Windows 7 Password with Password Reset Disk
Password reset disk only works on condition that you have created it before losing the account password. Therefore, you had better to create this win 7 password reset disk when you set up an account. Here is how to unlock windows 7 password with password reset disk.
Step 1: While typing a wrong win 7 password, a password hint will appear. Click “Reset password “, it will show you the Password Reset Wizard.
Step 2: Click NEXT and select your disk drive to reset the password with a new one.
Step 3: Then you can use the new password to log in your win 7 PC.
Solution 4: Unlock Windows 7 Password with Windows Password Key
In this situation you need to download Windows Password Key to unlock the lost windows 7 password.
Step 1: Download and install Windows Password Key in another accessible PC.
Step 2: Run the downloaded file to install Windows Password Key Standard. You can install it on any PC you have access to.
Step 3: Windows Start menu - From your Microsoft Windows Start Programs menu, select Windows Password Key Standard. It will be launched automatically.
Step4: Using a Windows Password Key bootable CD/DVD to reset Windows password or using a Windows Password Key bootable USB Flash Drive to reset windows password.
Any question please refer to http://resetwindows7passwords.blogspot.com/2014/06/how-to-unlock-windows-7-password.html