$(document).ready(function(){
    $("#lostpassword_form").submit(function(){
        var str = $(this).serialize();
        $.ajax({
            type: "POST",
            url: "ax/a.lostpassword.php",
            data: str,
            success: function(msg){
                $("#lost_response").ajaxComplete(function(event, request, settings){
                    $(this).html(msg);
                });
            }
        });
        return false;
    });
});