Php forgot password script

hello Everyone, my name is Marc Donald and I have a little problem with my forgot php script. In fact , I got the new random password in my mail but when I'm trying to login with that new password it does not work I don't know. I hope that I will found solution. Thanks
below is my code :
<?php include 'includes/header.php'; ?>
<?php
define('IN_SCRIPT', true);
// Start a session
//session_start();
include '../includes/settings.php';
if(isset($_SESSION['username']) == true )
{

header('location: index.php');
exit;
}



//Connect to the MySQL Database
include 'includes/settings.php';

//this function will display error messages in alert boxes, used for login forms so if a field is invalid it will still keep the info
//use error('foobar');
function error($msg) {


}

//This functions checks and makes sure the email address that is being added to database is valid in format.
function check_email_address($email) {
// First, we check that there's one @ symbol, and that the lengths are right
if(preg_match('#^(([a-z0-9!\#$%&\\\'*+/=?^_'{|}~-]+\.?)*[a-z0-9!\#$%&\\\'*+/=?^_'{|}~-]+)@(([a-z0-9-_]+\.?)*[a-z0-9-_]+)\.[a-z]{2,}$#i',$email)) {
// Email invalid because wrong number of characters in one section, or wrong number of @ symbols.
return false;
}
// Split it into sections to make life easier
$email_array = explode("@", $email);
$local_array = explode(".", $email_array[0]);
for ($i = 0; $i < sizeof($local_array); $i++) {
if(preg_match('#^(([a-z0-9!\#$%&\\\'*+/=?^_'{|}~-]+\.?)*[a-z0-9!\#$%&\\\'*+/=?^_'{|}~-]+)@(([a-z0-9-_]+\.?)*[a-z0-9-_]+)\.[a-z]{2,}$#i', $local_array[$i])) {
return false;
}
}
if(preg_match('#^(([a-z0-9!\#$%&\\\'*+/=?^_'{|}~-]+\.?)*[a-z0-9!\#$%&\\\'*+/=?^_'{|}~-]+)@(([a-z0-9-_]+\.?)*[a-z0-9-_]+)\.[a-z]{2,}$#i', $email_array[0])) { // Check if domain is IP. If not, it should be valid domain name
$domain_array = explode(".", $email_array[1]);
if (sizeof($domain_array) < 2) {
return false; // Not enough parts to domain
}
for ($i = 0; $i < sizeof($domain_array); $i++) {
if (!preg_match("^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|([A-Za-z0-9]+))$", $domain_array[$i])) {
return false;
}
}
}
return true;
}


if (isset($_POST['submit'])) {


if ($_POST['forgotpassword']=='') {
error('Please Fill in Email.');
}
if(get_magic_quotes_gpc()) {
$forgotpassword = htmlspecialchars(stripslashes($_POST['forgotpassword']));
}
else {
$forgotpassword = htmlspecialchars($_POST['forgotpassword']);
}
//Make sure it's a valid email address, last thing we want is some sort of exploit!
if (!check_email_address($_POST['forgotpassword'])) {
error('Email Not Valid - Must be in format of name@domain.tld');
}
// Lets see if the email exists
$sql = "SELECT COUNT(*) FROM users WHERE email = '$forgotpassword'";
$result = mysql_query($sql)or die('Could not find member: ' . mysql_error());
if (!mysql_result($result,0,0)>0) {
error('Email Not Found!');
}

//Generate a RANDOM MD5 Hash for a password
$random_password=md5(uniqid(rand()));

//Take the first 8 digits and use them as the password we intend to email the user
$emailpassword=substr($random_password, 0, 8);

//Encrypt $emailpassword in MD5 format for the database
$newpassword = md5($emailpassword);

// Make a safe query
$query = sprintf("UPDATE 'users' SET 'password' = '%s'
WHERE 'email' = '$forgotpassword'",
mysql_real_escape_string($newpassword));

mysql_query($query)or die('Could not update users: ' . mysql_error());

//Email out the infromation
$subject = "Your New Password";
$message = "Your new password is as follows:
----------------------------
Password: $emailpassword
----------------------------
Please make note this information has been encrypted into our database

This email was automatically generated.";
$site_name = 'xxx';
$site_email = 'xxx';
if(!mail($forgotpassword, $subject, $message, "FROM: $site_name <$site_email>")){
die ("Sending Email Failed, Please Contact Site Admin! ($site_email)");
}else{
error('New Password Sent!.');
}

}


else {
echo'<br /><br /><br /><br />';

echo' <form name="forgotpasswordform" class="" action="" method="post">
<div>Please enter your email address to get a new password</div><br />
<tr>
<td>Email Address:</td>
<td><input name="forgotpassword" required="required" type="text" value="" id="forgotpassword" /></td>
</tr>
<tr>
<td colspan="2" class="footer"><input type="submit" name="submit" value="Submit" class="mainoption" /></td>
</tr>
</table>
</form></div>';

}
?>
<?php include 'includes/footer.php' ?>

<?php ob_end_flush(); ?>