If your server is being upgraded you may need to upgrade your code to work with the php wersion running on your site.
Have it done for you, all the upgrades required on a stock install and all your add-ons, irrespective of the number you have installed.
Please check if the version of MySQL has been upgraded as well. If it has then your site may well need to be updated to work with the new version.
Please note: If it wasn't working before the upgrade, it will not work after the upgrade.