The first thing you should do is check whether you really forget login password or not. When we install Windows, it automatically creates an account “Administrator” and sets its password to blank. So if you have forget your user account password then try this:You can get into the Safe Mode to reset your account password from “Control Panel -> User Accounts”. In Safe Mode Windows will show this in-built Administrator account in Login screen.
But note that it just appears when you have enable it before or there is not other admin account exist.
Windows 7 also provide another method to recover forgotten Password by using “Reset Disk”. If you created a Password Reset Disk in Past, you can use that disk to reset the password.