ajax call not working

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jQuery

hi,

I am trying something using jquery ajax but it is not working .here is my code

if (txtUsername != "" && txtPassword != "") {
            debugger
            $.ajax({
                url: '/../UserData/User.json',
                dataType: 'json',
                success: function (data) {
                    $.each(data, function (obj, item) {
                        if (item.user_name == txtUsername && item.password == txtPassword) {
                            
                            window.location.href = "User/123.aspx?user=" + item.user_id + "";

                        }
                    });
                },
                error: function (data) {
                    alert('ERROR: Please Try Later ! ');
                }
            });
        }
        else {
            document.getElementById("<%=lblIncorrect.ClientID %>").style.display = "block";
        }
        return false;
    });

The if condition is true and it is entering to ajax call but nothing is returning. Directly it comes to return false line. when I debugged can't find any error also.

please help