Backup your Moodle data directory (same recommendation as above)
Backup your Moodle directory (same again...)
When your enter http://www.yoursite.dom/index.php what do you see?
If you see your site, you might be ok, check around.
If not, follow the upgrade instructions, here http://docs.moodle.org/en/Upgrading.
If your database is intact, as you indicate, you should be able to hook back in without loss of data (presuming none was lost when your host did their thing.)