email contact form not sending email in PHP

Question

I'm a new to coding, just started to learn for a project.

It's a website. In the email contact form, after clicking Submit, it won't send the message to my email, but it stays on the same page. My OS is Ubuntu, the files are all in the opt/lamp/hotdocs/project folder. Both Apache and Mysql are running. Below the PHP code, which is in the same file of the front-end file:

<?php
$statusMsg = '';
$msgClass = '';
if(isset($_POST['submit'])){
    // Get the submitted form data
    $email = $_POST['email'];
    $name = $_POST['name'];
    $message = $_POST['message'];

    // Check whether submitted data is not empty
    if(!empty($email) && !empty($name) && !empty($message)){

        if(filter_var($email, FILTER_VALIDATE_EMAIL) === false){
            $statusMsg = 'Please enter your valid email.';
            $msgClass = 'errordiv';
        }else{
            // Recipient email
            $toEmail = 'dilerniag@gmail.com';
            $emailSubject = 'Contact Request Submitted by '.$name;
            $htmlContent = '<h2>Contact Request Submitted</h2>
                <h4>Name</h4><p>'.$name.'</p>
                <h4>Email</h4><p>'.$email.'</p>
                <h4>Message</h4><p>'.$message.'</p>';

            // Set content-type header for sending HTML email
            $headers = "MIME-Version: 1.0" . "\r\n";
            $headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";

            // Additional headers
            $headers .= 'From: '.$name.'<'.$email.'>'. "\r\n";

            // Send email
            if(mail($toEmail,$emailSubject,$htmlContent,$headers)){
                $statusMsg = 'Your contact request has been submitted successfully !';
                $msgClass = 'succdiv';
            }else{
                $statusMsg = 'Your contact request submission failed, please try again.';
                $msgClass = 'errordiv';
            }
        }
    }else{
        $statusMsg = 'Please fill all the fields.';
        $msgClass = 'errordiv';
    }
}
?>

Then there is the page Contact.php, this is only the interested portion of code:

<div id="contact" class="container">

    <?php if(!empty($statusMsg)){ ?>
        <p class="statusMsg <?php echo !empty($msgClass)?$msgClass:''; ?>"><?php echo $statusMsg; ?></p>
    <?php } ?>

  <form action="" method="post"> 

  <h2 class="text-center">CONTACT</h2>
  <div class="row">
    <div class="col-sm-5">
      <p>Contact us</p>
      <p><span class="glyphicon glyphicon-map-marker"></span> Swords, North County, Dublin</p>
      <p><span class="glyphicon glyphicon-phone"></span> +00353 018904452</p>
      <p><span class="glyphicon glyphicon-envelope"></span> community.garde@gmail.com</p>
    </div>

    <div class="col-sm-7 slideanim">
      <div class="row">
        <div class="col-sm-6 form-group">
          <input class="form-control" id="name" name="name" placeholder="Name" type="text" required>
        </div>
        <div class="col-sm-6 form-group">
          <input class="form-control" id="email" name="email" placeholder="Email" type="email" required>
        </div>
        </div>
           <textarea class="form-control" id="message" name="message" placeholder="Message" rows="5" value="Click to send your comments"></textarea><br>
        <div class="row">
        <div class="col-sm-12 form-group">
          <button class="btn btn-default pull-right" type="submit">Send</button>
        </div>
      </div>

    </div>
  </div>
</div>
</form>

What can be the problem? Thank you.