Here is an example of a simple landing page with a navigation bar, a hero section, and a contact form in HTML:
```
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Landing Page</title>
<link rel="stylesheet" href="styles.css"> <!-- link to external stylesheet -->
</head>
<body>
<!-- Navigation Bar -->
<nav class="navbar">
<ul>
<li><a href="#home">Home</a></li>
<li><a href="#about">About</a></li>
<li><a href="#contact">Contact</a></li>
</ul>
</nav>
<!-- Hero Section -->
<section class="hero">
<h1>Welcome to Our Landing Page</h1>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed sit amet nulla auctor, vestibulum magna sed, convallis ex.</p>
<button>Get Started</button>
</section>
<!-- Contact Form -->
<section class="contact">
<h2>Get in Touch</h2>
<form>
<label for="name">Name:</label>
<input type="text" id="name" name="name"><br><br>
<label for="email">Email:</label>
<input type="email" id="email" name="email"><br><br>
<label for="message">Message:</label>
<textarea id="message" name="message"></textarea><br><br>
<input type="submit" value="Send">
</form>
</section>
<!-- Script tags for external JavaScript files -->
<script src="script.js"></script>
</body>
</html>
```
And here is an example of a simple stylesheet (in "styles.css" file):
```
body {
font-family: Arial, sans-serif;
margin: 0;
padding: 0;
}
.navbar {
background-color: #333;
color: #fff;
padding: 1em;
text-align: center;
}
.navbar ul {
list-style: none;
margin: 0;
padding: 0;
display: flex;
justify-content: space-between;
}
.navbar li {
margin-right: 20px;
}
.hero {
background-image: url('hero-image.jpg');
background-size: cover;
height: 100vh;
display: flex;
justify-content: center;
align-items: center;
color: #fff;
}
.hero button {
background-color: #333;
color: #fff;
border: none;
padding: 10px 20px;
font-size: 16px;
cursor: pointer;
}
.hero button:hover {
background-color: #444;
}
.contact {
padding: 2em;
}
.contact form {
display: flex;
flex-direction: column;
align-items: center;
}
.contact label {
margin-bottom: 10px;
}
.contact input, .contact textarea {
padding: 10px;
margin-bottom: 20px;
border: 1px solid #ccc;
}
.contact input[type="submit"] {
background-color: #333;
color: #fff;
border: none;
padding: 10px 20px;
font-size: 16px;
cursor: pointer;
}
.contact input[type="submit"]:hover {
background-color: #444;
}
```
This is just a basic example and you'll likely want to customize it to fit your needs. You'll also need to create the "hero-image.jpg" file and add it to the same directory as the HTML file.
Remember to create a new file for the JavaScript code (e.g. "script.js") and add it to the same directory as the HTML file.
Note: This code is not responsive, you may need to add media queries to make it responsive.