jquery file not found

<script src="jquery.js"></script>
<html>

<head>
<meta charset="UTF-8">
<!--<script type="text/javascript" charset="UTF-8" src="jquery.js"></script>-->
<script type="text/javascript">
    function sendd() {
        var firstname = $("#firstname").val();
        var lastname = $("#lastname").val();
        if ($.trim(firstname).length > 0 & $.trim(lastname).length > 0) {
            $.ajax({
                type: "POST", //Request type
                url: "http: /localhost/firstname.php",
                data: {
                    firstname: firstname,
                    lastname: lastname
                },
                cache: false,
                success: function(data) {
                    alert(data);
                }
            })
        } else {
            alert("Input fields are empty");
        }
    }
</script>
</head>

<body>
    
    <input type=”text” placeholder=”write your first name” id=”firstname”>
    <input type=”text” placeholder=”write your last name” id=”lastname”>
    <button id="sub" onclick="sendd()">Submit result</button>
</body>

</html>

error:
GET file:///C:/Users/kalat/Documents/random%20projects%20c++%20or%20py%20or%20phpor%20html%20or%20css/android/Hello/www/jquery.js net::ERR_FILE_NOT_FOUND