after clicking submit button a white page appears - php

Question

I have made form using HTML n CSS and also linked action to my PHP file index_handler.php just don't understand where is the mistake that a strange white screen appears when I press submit
<form action="index_handler.php" class="appointment-form ftco-animate" method="post" name="form">
<div class="d-md-flex">
<div class="form-group">
<input type="text" class="form-control" name="name" placeholder="Full Name ">
</div>
<div class="form-group ml-md-4">
<input type="text" class="form-control" name="m_name" placeholder="Mother's Name">
</div>
<div class="form-group ml-md-4">
<input type="email" class="form-control" name="email" placeholder="Email ID">
</div>
</div>
<div class="d-md-flex">
<div class="form-group">
<div class="form-field">
<div class="select-wrap">
<div class="icon"><span class="ion-ios-arrow-down"></span></div>
<select name="course" id="" class="form-control">
<option value="text" style="color:black" >Select Course</option>
<option value="text" style="color:black" >Regular Classroom Programme</option>
<option value="text" style="color:black" >Distance Learning Programme</option>
<option value="text" style="color:black" >Online Learning Programme</option>
<option value="text" style="color:black" >School Integrated Programme</option>
<option value="text" style="color:black" >Crash Course Programme</option>
<option value="text" style="color:black" >Summer Course Programme</option>
<option value="text" style="color:black" >Edu-Nexus Programme</option>
</select>
</div>
</div>
</div>
<div class="form-group">
<div class="form-field">
<div class="select-wrap">
<div class="icon"><span class="ion-ios-arrow-down"></span></div>
<select name="board" id="" class="form-control">
<option value="text" style="color:black" > Board</option>
<option value="text" style="color:black" >CBSE</option>
<option value="text" style="color:black" >CHSE(STATE)</option>
<option value="text" style="color:black" >ICSE</option>
</select>
</div>
</div>
</div>
<div class="form-group">
<div class="form-field">
<div class="select-wrap">
<div class="icon"><span class="ion-ios-arrow-down"></span></div>
<select name="class" id="" class="form-control">
<option value="text" style="color:black" > Class</option>
<option value="text" style="color:black" >VI</option>
<option value="text" style="color:black" >VII</option>
<option value="text" style="color:black" >VIII</option>
<option value="text" style="color:black" >IX</option>
<option value="text" style="color:black" >X</option>
<option value="text" style="color:black" >XI</option>
<option value="text" style="color:black" >XII</option>
<option value="text" style="color:black" >XIII</option>
<option value="text" style="color:black" >Others</option>
</select>
</div>
</div>
</div>
</div>
<div class="d-md-flex">
<div class="form-group">
<textarea name="address" id="" cols="30" rows="2" class="form-control" placeholder="Address"></textarea>
</div>
<div class="form-group ml-md-4">
<input type="tel" name="phone" class="form-control" placeholder="Phone">
</div>
<div class="form-group ml-md-4">
<input type="submit" value="Request A Quote" class="btn btn-secondary py-3 px-4">
</div>
</div>
</form>
so here is my PHP file i.e, index_handler.php
<?php
if(isset($_POST['submit'])){
$name=$_POST['name'];
$email=$_POST['email'];
$m_name=$_POST['m_name'];
$course=$_POST['course'];
$board=$_POST['board'];
$class=$_POST['class'];
$address=$_POST['address'];
$phone=$_POST['phone'];
$to='rajkishore.panda2000#gmail.com';
$subject='Form Submission';
$message="Name :".$name."\n"."Mother's Name :".$m_name."\n"."Course :".$course."\n"."Board :".$board."\n"."Class :".$class."\n"."Phone :".$phone."\n"."Address:"."\n\n".$address;
$headers="From: ".$email;
if(mail($to, $subject, $message, $headers)){
echo "<h1>Sent Successfully! Thank you"." ".$name.", We will contact you shortly!</h1>";
}
else{
echo "<h1>Something went wrong!</h1>";
}
}
?>

Answer 1

You need give submit button name, because your php is
isset($_POST['submit'])
to fix your problem, change your code
<input type="submit" value="Request A Quote" class="btn btn-secondary py-3 px-4">
to
<input type="submit" name="submit" value="Request A Quote" class="btn btn-secondary py-3 px-4">

Answer 2

Hey just Add name="submit" and that's it
change this code
<div class="form-group ml-md-4">
<input type="submit" value="Request A Quote" class="btn btn-secondary py-3 px-4">
</div>
To be
<div class="form-group ml-md-4">
<input type="submit" name="submit" value="Request A Quote" class="btn btn-secondary py-3 px-4">
</div>