How to check if the form has been submitted on localhost - php

Question

I'm trying to check if the form has been submitted. If I press the submit button, the success message will appear but when I check my mailbox I don't see any message. I'm using WampServer. I followed a YouTube tutorial where the guy has the exact same code but for some reason, it doesn't work for me.
<form action="contact.php" method="post" id="myForm">
<div class="md-form">
<i class="fas fa-user prefix grey-text"></i>
<input type="text" required name="name" id="form_name" class="form-control" />
<label for="form_name">Your name</label>
</div>
<div class="md-form">
<i class="fas fa-envelope prefix grey-text"></i>
<input type="email" required name="email" id="form_email" class="form-control" />
<label for="form_email">Your email</label>
</div>
<div class="md-form">
<i class="fas fa-tag prefix grey-text"></i>
<input type="text" name="subject" required id="form-Subject" class="form-control" />
<label for="form_subject">Subject</label>
</div>
<div class="md-form">
<i class="fas fa-pencil-alt prefix grey-text"></i>
<textarea id="form_text" name="message" class="form-control md-textarea" rows="3"></textarea>
<label for="form_text">Your message</label>
</div>
<div class="text-center mt-4">
<button class="btn contact-button text-white" type="submit" name="submit">Submit</button>
</div>
<div id="success_message" class="text-dark text-center"></div>
</form>
<?php
if(isset($_POST['submit']))
{
$name = $_POST['name'];
$subject = $_POST['subject'];
$mailFrom = $_POST['email'];
$message = $_POST['message'];
$mailTo = "patriciushorny#gmail.com";
$headers = "From: ".$mailFrom;
$txt = "You have recieved an e-mail from ".$name.".\n\n".$message;
mail($mailFrom, $subject, $txt, $headers);
header("Location: index.php?mailsend");
}
?>

Answer 1

<form class="form-area contact-form text-right" action="mail.php" method="post">
<div class="row">
<div class="col-lg-6 form-group">
<input name="name" id="name" placeholder="Enter your name" class="common-input mb-20 form-control" type="text">
<input name="email" id="email" placeholder="Enter email address" class="common-input mb-20 form-control" type="email">
<input name="sub" id="sub" placeholder="Enter subject" class="common-input mb-20 form-control" type="text">
</div>
<div class="col-lg-6 form-group">
<textarea class="common-textarea form-control" name="desc" id="desc" placeholder="Enter Messege" ></textarea>
</div>
<div class="col-lg-12">
<button class="genric-btn primary" value="submit" id="submit" name="submit" style="float: right;">Send Message</button>
</div>
</div>
More Details view this link VIEW FULL CODE