PLEASE HELP

I don’t know what i do whit this:
What can i do please?

Fatal error: Call to undefined method WC_Shipping::get_available_shipping_methods() in /homepages/13/d455391896/htdocs/wp-content/themes/theretailer/woocommerce/checkout/review-order.php on line 14

https://wordpress.org/plugins/woocommerce/