Password reset PHP

I am new to website design and I have recently made a website and i would like to add a reset password function, it doesn't work.

The SQL connection is inside of the init.php file

<?php
include('core/init.php');
include('includes/overall/header.php');
echo "
<h1>Reset Password</h1>


<div class='Reset' align='center'>
<form action='forgot_pass.php' method'POST'>
Enter your username<br><input type='text' name='username'><p>
<br>
Enter your email<br><input type='email' name='email'><p>
<input type='submit' value='Submit' name='submit'>
</form>
</div>
";

if (isset($_POST['submit']))
{
$username = $_POST['username'];
$email = $_POST['email'];

$query = mysql_query("SELECT * FROM `users` WHERE `username`='$username'");
$numrow = mysql_num_rows($query);

if ($numrow!=0)
{
    while($row = mysql_fetch_assoc($query))
    {
        $db_email = $row['email'];
    }
    if ($email == $db_email)
    {
        $code = rand(10000,1000000);

        $to = $db_email;
        $subject = "Password Reset";
        $body = "

        Automated email. Click the link
        http://ift.tt/1U1Buug

        ";

        mysql_query("UPDATE users SET passreset='$code' WHERE username='$username'");
        mail($to,$subject,$body);

        echo "Check Email";
    }
    else
    {
        echo "Email not correct";
    }
} else {
    echo "That user does not exist";
    }


}

?>

I will be so happy if somebody could help me thanks