Windows 7 allows us to create a Windows password reset disk (USB key) in case that we lost the Win 7 logon password. When we lose the password of Win 7, we can reset a new one with the created disk. The weak point is that you can only create the disk before losing your Windows 7 password. If you do not create that, it could not help.
If you have an available administrator account on your system, you can get your password back easily. Logon Win 7 system with the admin account, and then you can come to the Control Panel and change or delete other accounts' passwords. Just three steps:
Step 1: Click Start -> Control Panel -> Add or remove user accounts
Step 2: Choose the locked administrator account
Step 3: Click Change the password or Remove the password. And then you can change or remove the lost or forgotten password
If you do not have another available administrator account, you could try some third party software. There is plenty of third party software for password recovery on Windows 7 online. all of them are designed to create a Windows password recovery disk. With the disk you can recover your lost Windows 7 password. I highly recommend Windows Password Recovery Tool 3.0 and use it as an example. What you need to do is just three steps (you need another computer to create the disk):
Step 1: Download Windows Password Recovery Tool 3.0
Step 2: Burn a Windows password recovery disk with the software
Step 3: Recover the Windows 7 password with the disk
I think the most efficient is using third party windows password recovery software. Have a try.