Not redirecting to thankyou.php after place order

After pressing place order button it redirects to http://sitename.com/cart
even Order Received page(http://sitename.com/checkout/order-received/) is also redirecting me to http://sitename.com/cart. How can I redirect customers to actual thankyou page!? Any help? any function? or anything?!

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