registration form maintain when it reload

I have one registration form.In that name,address,gender,country,state,city,...feilds are there.There is combo box of country and when we select the country the states according to the selected country is reload in the state combo box.But when i select the state the value of above text box name,address,gender is been blank.so how can i maintain the value of above textbox when i select the state combo box.Pls answer me as soon as possible!!!!!!

re: registration form maintain when it reload

You can retrieve the field values ($_GET or $_POST) and insert them in your form as default values or (in case of select fields) adjust the selected attribute according to your input values.