Create Short Code for Custom Post Type with WordPress Custom Plugin

Shortcode.php

<?php
/*
Plugin Name: My Shortcode Plugin
Description: display custom post type using short code.
Version: 1.0
Author: Author Name
*/
// register custom post type to work with
add_action('init', 'webr_faq_post_type');
function webr_faq_post_type() {
	register_post_type('webr_faq', array(
	'label' => 'Faq',
	'description' => '',
	'public' => true,
	'show_ui' => true,
	'show_in_menu' => true,
	'capability_type' => 'post',
	'map_meta_cap' => true,
	'hierarchical' => false,
	'rewrite' => array('slug' => 'faq', 'with_front' => true),
	'query_var' => true,
	'supports' => array('title','editor','excerpt','thumbnail','author','page-attributes'),
	'labels' => array (
		'name' => 'Faq',
		'singular_name' => 'Faq',
		'menu_name' => 'Faq',
		'add_new' => 'Add Faq',
		'add_new_item' => 'Add New Faq',
		'edit' => 'Edit',
		'edit_item' => 'Edit Faq',
		'new_item' => 'New Faq',
		'view' => 'View Faq',
		'view_item' => 'View Faq',
		'search_items' => 'Search Faq',
		'not_found' => 'No Faq Found',
		'not_found_in_trash' => 'No Faq Found in Trash',
		'parent' => 'Parent Faq',
		)
	)
	);
}

add_action('init', 'webr_faq_post_type_taxonomy');
function webr_faq_post_type_taxonomy() {
	register_taxonomy( 'webr_faq_categories',array (
	0 => 'webr_faq',
	),
	array( 'hierarchical' => true,
	'label' => 'FAQ Categories',
	'show_ui' => true,
	'query_var' => true,
	'show_admin_column' => true,
	'labels' => array (
	'search_items' => 'Faq Category',
	'popular_items' => '',
	'all_items' => '',
	'parent_item' => '',
	'parent_item_colon' => '',
	'edit_item' => '',
	'update_item' => '',
	'add_new_item' => 'Add New Faq Category',
	'new_item_name' => 'New Faq Category',
	'separate_items_with_commas' => '',
	'add_or_remove_items' => '',
	'choose_from_most_used' => '',
	)
	)
	);
}

function cpt_content_func($atts){
	
	extract( shortcode_atts( array(
	'slug' => null,
	'post_type'=>null,
	), $atts ) );

	$args = array(
			'name' => $slug,
			'post_type' => $post_type,
			'posts_per_page' => 2
	);
	$posts= array();
	$posts = get_posts( $args );
//echo "<pre>";
//print_r($posts);
	$content='';
	$post_nav=array();
	foreach ($posts as $post) : setup_postdata($post);
		$post_nav[] += $post->ID;
	 	$url = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID) );
		$content .= '<h2>'.$post->post_title.'</h1>';
		if(!empty($url)){
			$content .= '</br><img src='.$url[0].'>';
		}
		$content .= '</br></br>'.$post->post_content;
		$content .= '<div class="nav-previous">' . get_next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts' ) ) . '</div>';

	endforeach; 
	
	$current = array_search( get_the_ID(), $post_nav );
	$prevID = $posts[$current-1];
	$nextID = $posts[$current+1];
	
	$content .= '<div class="navigation">';
	if ( !empty( $prevID ) ):
		$content .= '<div class="alignleft">';
		$content .=  '<a href='.get_permalink( $prevID ).' title='.get_the_title( $prevID ).'>Previous</a>';
		$content .= '</div>';
	endif;
	if ( !empty( $nextID ) ):
	$content .= '<div class="alignright">';
	$content .= '<a href='.get_permalink( $nextID ).' title='.get_the_title( $nextID ).'>Next</a>';
	$content .= '</div>';
	endif;
	$content .= '</div>'; //navigation
	
	return $content.wp_reset_postdata();

}

add_shortcode('rep','cpt_content_func');


?>