I want to implement a self reset password functionality for Windows users. When the Logon screen prompts the domain users should be presented with a forgot password button which will take the user to a passwrod reset wizard. So the problem is how to add a command button to the standard windows logon screen.
For implementation of login/authentification in Windows you may read about GINA,
GINA is a replaceable dynamically linked library that is loaded early in the boot process in the context of Winlogon when the machine is started
Modifying login screens is a rather obscure science.
For Windows XP and below, you will need to create a custom GINA (Graphical Identification and Authentication) DLL. This process is described in this MSDN magazine article.
As for Vista and above, you will need to create a custom Credential Provider. It is demonstrated in this MSDN magazine article.
I wouldn't recommend doing what you are doing. This could be a huge security breach.
That would depend hugely on the OS; pre-vista, GINA; post-vista, LogonUI can be extended by a custom credential provider (as discussed here). However, it won't be easy - and probably risky too.