The requested URL was not found on this server. on php codeigniter

Question

I am a beginner to codeigniter and, I'm trying to make an inventory system. The dashboard is ready, but when I click a button on dashboard it gives an error, it is not loading the new product view I defined the routes tried much but no positive result

Here is my controller

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Dashboard extends CI_Controller {

    public function _construct(){
        parent::_construct();
        $this->load->database();

        $this->load->model("m_inventory");
        $this->load->helper('form');
        $this->load->library('form_validation');
    }

    public function add_items(){
        $this->load->view('newproduct');
    }
}

And my dashboard view

<div class="form">
    <h2>Inventory System</h2>
    <div class="button1">
        <a title="New account" href='<?php echo base_url ('dashboard/add_items'); ?>New product</a> 
    </div> 
    <div class="button2">
        <input type="submit" name="submit" value="Current Stock" > 
    </div>
</div>

Answer 1

1. Confirm if url helper is loaded in application/config/autoload.php since you are using base_url()
2. Your view file name should be newproduct.php
3. Check by adding/removing index.php after base url.

If above doesn't help you then share the error you are getting and CI version.