Hi,
PDO is a PHP extension that is only available in PHP 5.0 and later. If you have PHP 5.0 or later then I can install PDO in no time. If not, the issue is more complicated, we need to have 2 versions of PHP installed in paralell (so any other sites that you run on your server won't break). I can do that too but it takes a lot more time and I will charge you a little more.
About the hacked site: what do you mean "hacked"? Was it defaced, the database compromised, etc? Does the site use any known CMS systems / frameworks, like Joomla, Drupal, etc? It's OK if you don't know, I can see it for myself if you provide a link to the site.
Ready to start.