get_the_title external php

hi folks..

I created one external php file. here the example code hello.php

function hello($title, $cfield)
    {
.....
    }

  $title = get_the_title();
	$cfield = get_post_meta($post->ID, "keyword", true);
  $text = hello($title, $cfield);

   echo $text;

this code will load by ajax external content. my problem here how to get a correct id for get_the_title and get_post_meta.

let me know the hints to call a correct ID for external file.