Right so I'd suggest on the live site installing akeeba backup (core) this is the free version
I'd suggest with backup completed and downloaded to the localhost
I'd try and update to latest Joomla3 version and see if that corrects the problem
If this does not work try and re-install the core files via the update component
I would not do any of the above to the live site till you know it works on the localhost version
Are you familiar with how to re-install the core Joomla files?
Cheers
Paul