HELP!! Please..

I have been trying to fix this for hours and i'm at a loss. As far as I know, nothing was changed in admin settings or files.

Once you complete step 3 of checkout, instead of taking you to the confirmation page, this error is coming up...

Fatal error: Class 'PHPMailer' not found in /home/b-web/b3/b0/thestampspot.com.au/public/www/catalog/includes/functions/functions_email.php on line 138

This is what I have for line 138
$mail = & new PHPMailer();

Also, It isnt generating an 'order email'. I only know there are orders if I login to admin panel.

Can anyone please enlighten me? Any help would be really appreciated!