How create popup and redirect current page to edit form

Question

After click 'Send' button, there will be a confirm box to double confirm the phone number and message to be send. If click 'Confirm' the message will be send and if click 'Cancel' the pop up will redirect the page to edit the phone number and message. Coding for the 'Confirm' button is done and success but coding for the 'Cancel' button is unsuccessful. It direct to the page but the inputs all gone. How to make the input still in the textbox after click 'Cancel' button like picture below?