You are sending data as JSON but are trying to read through querystring.
Use like this
$("#saveChanges").click(function () {
$.ajax({
url: "../handlers/adminSaveResults.ashx?pinNovo=123456",
type: "POST",
data: {},
async: true,
contentType: "application/json; charset=utf-8",
dataType: 'json',
success: function (data) {
alert("Dados Guardados! ;)");
},
error: function (data) { alert("ERRO: " + data.status); },
timeout: 15000
});
}
Now you can receive data in query string.