Dear Sir/Madam,
I have written a code as follows

<?php

require_once(dirname(dirname(_FILE_)) . '/lib/messagelib.php');
$eventdata = new stdClass();
$eventdata->component = 'mod_quiz'; //your component name
$eventdata->name = 'submission'; //this is the message name from messages.php
$eventdata->userfrom = 4;
$eventdata->userto = 3;
$eventdata->subject = 'Assigment No.2';
$eventdata->fullmessage = "This is second assignment to test the message from outside";
$eventdata->fullmessageformat = FORMAT_PLAIN;
$eventdata->fullmessagehtml = 'Hello World';
$eventdata->smallmessage = 'Check Your Assigment';
$eventdata->notification = 1; //this is only set to 0 for personal messages between users
events_trigger('message_send', $eventdata);

?>

When run the php file there is no error, no any warning nor any working.

The objective behind this code is to send a message from a page my own created without being logged in by using just my id and message receiver id. How I can do this. Please guide me in this regard.