Hamburger Menu for mobile not working

1. Bootstrap 3 and jQuery 1 are outdated.   The current release version of Bootstrap is 4.x and version 5.2 is in beta release.  jQuery 3 has been out for quite a while.  You have some catching up to do. 

2. Your navbar is broken because it was not built correctly.

Start over with this as your base.  

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap 4.5 Starter</title>

<link rel="stylesheet" href="
https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css">

</head>
<body>
<nav id="topNav" class="navbar navbar-top navbar-expand-lg navbar-dark bg-dark"> <a class="navbar-brand mx-auto" href="index.html"> 
<!--Your logo goes here--> 
<img class="shadow-sm rounded-circle" src="https://dummyimage.com/250x110" alt="logo/brand"> </a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target=".navbar-collapse"> <span class="navbar-toggler-icon"></span></button>
<div class="navbar-collapse collapse">
<ul class="navbar-nav ml-auto">
<li class="nav-item current"><a class="nav-link" href="#">Home</a></li>
<li class="nav-item dropdown"> <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Services</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown"> <a class="dropdown-item" href="#">sub-1a</a> <a class="dropdown-item" href="#">sub-1b</a> <a class="dropdown-item" href="#">sub-1c</a> </div>
</li>
<li class="nav-item"><a class="nav-link" href="#">About</a></li>
<li class="nav-item"><a class="nav-link" href="#">Contact</a></li>
</ul>
</div>
</nav>
<div class="jumbotron jumbotron-fluid text-center">
<h1 class="display-5">Bootstrap 4.5  with Dreamweaver 2021</h1>
<p class="lead">Easily build your page using the Bootstrap components from the Insert panel.</p>
<hr class="my-4">
<p>This is a simple hero unit, a simple jumbotron-style component for calling extra attention to featured content or information.</p>
<p class="lead"> <a class="btn btn-dark btn-lg" href="https://getbootstrap.com/docs/4.0/components/jumbotron/" role="button">Learn more</a> </p>
</div>
<div class="container-fluid">
<div class="row text-center">
<div class="col-md-6 col-lg-3">
<h3>Heading 3</h3>
<img class="img-fluid" src="https://dummyimage.com/900x600" alt="placeholder">
<p>Lorem ipsum dolor...</p>
 
</div>
<div class="col-md-6 col-lg-3">
<h3>Heading 3</h3>
<img class="img-fluid" src="https://dummyimage.com/900x600" alt="placeholder">
<p>Lorem ipsum dolor...</p>
</div>
<div class="col-md-6 col-lg-3">
<h3>Heading 3</h3>
<img class="img-fluid" src="https://dummyimage.com/900x600" alt="placeholder">
<p>Lorem ipsum dolor...</p>
</div>
<div class="col-md-6 col-lg-3">
<h3>Heading 3</h3>
<img class="img-fluid" src="https://dummyimage.com/900x600" alt="placeholder">
<p>Lorem ipsum dolor...</p>
</div>

</div>
<hr class="my-4">
<div class="row">
<footer class="col"> <small>© 2021 Footer goes here</small> </footer>
</div>
</div>


<!--first jQuery then popper then Bootstrap js--> 
<script src="https://code.jquery.com/jquery-3.5.1.min.js" integrity="sha256-9/aliU8dGd2tb6OSsuzixeV4y/faTqgFtohetphbbj0=" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>
</body>
</html>

NOTE:  Beginning with Bootstrap 4, float layouts were replaced with newer flexbox layouts.  Old utility classes were removed and new classes were added. 

• https://www.w3schools.com/bootstrap4/
• https://getbootstrap.com/docs/4.6/getting-started/introduction/

Hope this helps.  Post back if you have any questions.