if document.ready function not working after click on next button use .live with change event

if document.ready function not working after click on next button. or post back not working
then use .live function
$(document).ready(function()
{
$("#input_1_16").live('change',function()
{
var id=$(this).val();
var dataString = 'id='+ id;
//alert("hello");
$.ajax
({
type: "POST",
url: " http://therapy.leadingedgeinfosolutions.com/ajax_city.php",
data: dataString,
cache: false,
success: function(html)
{
$("#input_1_50").html(html);
//alert(html);
}
});

});
});