when i try to reset password by clicking forget password . and then provide email or username
it gives this error message :"error while processing the requested operation"
Have you set your e-mail accounts in your LMS? The error message you quoted means that the system cannot send e-mail. So it's either you left the dummy e-mail address instead of inserting your desired e-mail sender, or that your server doesn't have the permission to send e-mails from an application. Or both