Fatal error: Class 'WC_Order' not found

Hello, I had a plugin made and now, randomly I’m receiving this error below.

‘[Wed Jun 22 17:37:51.241380 2016] [:error] [pid 21875] [client 2601:644:4202:7270:f08b:7b3f:acff:7b33:15246] PHP Fatal error: Class ‘WC_Order’ not found in /nas/content/live/camoeyes/wp-content/plugins/woo-rx-varification/rx-verification.php on line 374, referer: https://camoeyes.com/wp-admin/plugins.php?plugin_status=active’

I’ve looked at line 374 which is the line $order = new WC_Order( $post_id );

And I’m not sure what could be wrong with it..

I wont likely be able to get help from the person who made it for me for a long time and my site is going to be dead until then.

If anyone can help me understand what might be wrong I will virtually hug the hell out of you

‘<?php
/**
*Plugin Name: Lens RX Verification V2
*Plugin URI: https://www.redsymboltechnologies.com/
*Version: 2.0
*Author: Red Symbol
*Description: This plugin work for Lens RX Verification
*/
if ( ! defined( ‘ABSPATH’ ) ) exit; // Exit if accessed directly

/*==================================================================
@ Defining Global For Plugin
==================================================================*/’

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