title: return to previous page with form complet
body: <p>Basically I have a registration form and when I click the submit button check if the email is valid.</p>
  
  <p>However if there is a record of an error I do "header (" location: ". $ _SERVER ['HTTP_REFERER']);" to go to previous page.
  When this happens you need to write it all again in the form, how can I make the data to be filled?</p>