Magento 1.9 go to payment methods step after cancel payment

Question

I'm working on magento site which have code to show payment method, after some user went to payment and cancel it.

ex- user fills the checkout steps and go to paypal, when cancel the paypal payment he redirect to checkout page and show the payment method section.

i'm using magento default one page checkout.

i use this code for load payment step

function onCompleteAjaxOpc(arg) {
                        shippingMethod.nextStep(arg);
                        fieldsetOpc.show();
                        jQuery('#opc-loader').hide();


                        jQuery('#top-shipping_method').on('click', function() {
                            new Ajax.Request('<?php echo Mage::getUrl('checkout/onepage/getShippingMethod'); ?>', {method: 'get', onComplete: function(arg) {
                                billing.nextStep(arg);
                            }});
                        })

                    }
                    new Ajax.Request('<?php echo Mage::getUrl('checkout/onepage/getPayment'); ?>', {method: 'get', onComplete: onCompleteAjaxOpc });

But the ajax url shows 404

https://devsite.mydoman.comain/checkout/onepage/getPayment/

Anyone know how to show payment method block after cancel payment and return to site, Thank You