You had a damage disk and he ran the disk utility which has to be done while the start u disk is unmounted so you boot from the install disk instead of the hard drive with your system.

You can do this yourself there are two utilities for repair one is disk first Aid which the IT used and the other is repair permissions which he probably also used for peace of mind.

You can run the repair permissions while booted from the start up disk. But you must boot from the install disk in order to repair the disk with Disk First Aid.

You find the Disk Utility in the Applications folder then in the Utilities folder.

You should periodically check the permissions and you can also verify the disk without booting from the install disk.