SMTP Error: Could not authenticate. Message could not be sent.

function supervisorMail(){

global $error;
$mail = new PHPMailer();
$mail->IsSMTP();
$mail->SMTPDebug = 0;
$mail->SMTPAuth = true;
$mail->SMTPSecure = 'ssl';
$mail->Host = 'smtp.gmail.com';
$mail->Port = 465;
$mail->Username = "***@gmail.com";
$mail->Password = "****";
$mail->SetFrom("***@gmail.com", "Employee Leave Management System");

$userID=$_SESSION['userID'];

$select_query = mysql_query("SELECT * FROM employee WHERE emp_id = '$userID'");
$select_sql = mysql_fetch_array($select_query);
$name=$select_sql['manager_name'];
var_dump($name);

$select_query1 = mysql_query("SELECT email FROM employee WHERE emp_id='$name'");
$select_sql1 = mysql_fetch_array($select_query1);
$email=$select_sql1['email'];
    var_dump($email);

$mail->Subject = "subject ";
$mail->Body = "something.";
$mail_to = $email;
$mail->AddAddress($mail_to);

if(!$mail->Send())
{
    echo "Message could not be sent. <p>";
    echo "Mailer Error: " . $mail->ErrorInfo;
    exit;
}

echo "Message has been sent";

$mail->Username = "@gmail.com";
$mail->Password = "";

$mail->Username = "********@gmail.com";
$mail->Password = "********";

<?php
require 'PHPMailer/PHPMailerAutoload.php';
$mail = new PHPMailer;
$mail->SMTPDebug = 2;    // Enable verbose debug output
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host = 'smtp.gmail.com';  // Specify main and backup SMTP servers
$mail->SMTPAuth = true;   // Enable SMTP authentication
$mail->Username = '*****001@gmail.com';  // SMTP username
$mail->Password = 'ma****02';    // SMTP password
$mail->SMTPSecure = 'tls'; // Enable TLS encryption, `ssl` also accepted
$mail->Port = 465; // TCP port to connect to
$mail->setFrom('ravi******@gmail.com', 'Mailer'); // Add set from id
$mail->addAddress('er.ravihirani@gmail.com', 'Ravi Hirani');     // Add a recipient
//$mail->addAddress('ellen@example.com');               // Name is optional
//$mail->addReplyTo('info@example.com', 'Information');
//$mail->addCC('cc@example.com');
//$mail->addBCC('bcc@example.com');
//$mail->addAttachment('/var/tmp/file.tar.gz');         // Add attachments
//$mail->addAttachment('/tmp/image.jpg', 'new.jpg');    // Optional name
//$mail->isHTML(true);   // Set email format to HTML
$mail->Subject = 'Here is the subject';
$mail->Body    = 'This is the HTML message body <b>in bold!</b>';
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';
if(!$mail->send()) {
    echo 'Message could not be sent.';
    echo 'Mailer Error: ' . $mail->ErrorInfo;
} else {
    echo 'Message has been sent';
}

global $password; // <- this added to make script work

        $mail = new PHPMailer(true);
        try {
            $mail->isSMTP();

            // Set mailer to use SMTP
            $mail->Host = '*******.com';
            $mail->SMTPAuth = true;
            $mail->Username = 'no-reply@*******.com';
            $mail->Password = $password;
            $mail->SMTPSecure = 'tls';
            $mail->Port = 587;
            $mail->setFrom('no-reply@*******.com', '******* - DO NOT REPLY');

            //$mail->isHTML(true);
            $mail->AddAddress($user->email);

            $mail->Subject = "*******";
            $mail->Body    = "*******";

            $mail->send();

        } catch (Exception $e) {
            echo 'Message could not be sent. Mailer Error: ', $mail->ErrorInfo;
        }