Forgot my windows password trying to reset it

Most time Offline NT Password & Registry Editor tool can help reset Windows password. But that program cannot guarantee 100% reset though that is free. When that way is failed or when you need quick and effective way you can try Windows Login Recovery, which I have tried before.
Windows Login Recovery Secure Windows Password Recovery Tool

In fact, when we lost Windows password the best way is admin password or reset disk. If you have one of them you can try them at first. But when all you don't have I think the quickest and the best way will be reset software. For my experience, for reset software I prefer to Anmosoft Windows Password Reset, which can help reset, change or create a user password, and you can know more from:
http://www.resetwindowspassword.com

You did not mention that you are talking about user account password or administrator account password. User account password can be changed or removed by logging in as administrator (if you have access to administrator password). On the other hand the easiest way to reset administrator password is by using Windows password recovery software. You can click (or can search yourself) http://lmgtfy.com/?q=Windows+Password+Recovery+Software+To+Reset+Windows+Password to get effective password recovery software.

Admin twice is the default password