The first thing which you check if you forget login password. 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:
Start system and when you See Windows Welcome screen / Login screen, press ctrl+alt+del keys Twice and it’ll show Classic Login box. Now type “Administrator” (without quotes) in Username and leave Password field blank. Now press Enter and you should be able to log in Windows.
Now you can reset your account password from “Control Panel -> User Accounts”.
Same thing can be done using Safe Mode. In Safe Mode Windows will show this in-built Administrator account in Login screen.

Windows XP and further versions 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.