Get Page by Title in WordPress. More details at http://sudarmuthu.com/blog/retrieving-posts-and-pages-based-on-title-in-wordpress

get-multiple-posts-by-title.php

/**
 * Retrieve posts ids given their title.
 * Use this function if there are more than one post with the same title.
 */
function get_multiple_posts_by_title($title) {
    global $wpdb;
    $posts_ids = array();

    $posts = $wpdb->get_results( $wpdb->prepare( “SELECT ID FROM $wpdb->posts WHERE post_title = %s AND     post_type=’post_type’”, $title), OBJECT );
    foreach ($posts as $post) {
         $posts_ids[] = $post->ID;
    }

    return $posts_ids;
}

get-page-by-title.php

$page = get_page_by_title('post title that we are searching');
// $page is the post array. To just retrieve the id
$id = $page->ID;

get-post-by-title.php

/**
 * Retrieve a post given its title.
 *
 * @uses $wpdb
 *
 * @param string $post_title Page title
 * @param string $output Optional. Output type. OBJECT, ARRAY_N, or ARRAY_A.
 * @return mixed
 */
function get_post_by_title($page_title, $output = OBJECT) {
    global $wpdb;
        $post = $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_title = %s AND post_type='post'", $page_title ));
        if ( $post )
            return get_post($post, $output);

    return null;
}