This is a controller, please follow this pattern, it always work for me

Sender.php

<?php
class Sender extends CI_Controller {
	public function __construct() // to remember use public
    {
        parent::__construct();
        $this->load->helper('url');

    }
	public function home() {
		$this->load->library('email'); // load email library
		$this->email->set_newline("\r\n");
		$this->email->from('cictpracticum2015@gmail.com', 'Sample Po');
		$this->email->to('earljohn3ric@gmail.com');
		$this->email->subject('Sample');
		$this->email->attach('/var/www/html/sample.txt');
		$message = "Mahal ko si Char and Mahal ako ni Char :D";
 		$this->email->message($message);
		if ($this->email->send()){
			echo "Mail Sent!";
		} else {
			show_error($this->email->print_debugger());
		}
	}
}