Restoring Lost OS X Files
If you erase or otherwise "lose" an OS X system component, application or utility (such as Mail or Disk Utility, for example) you can restore them without having to reinstall OS X.
Download the shareware utility
Pacifist. Read the documentation. Use Pacifist to extract a fresh copy of the missing application from the file archives on your OS X Installer disc. The file archives are usually found on the installer disc in the /System/Installations/ folder. Insert the Installer Disc in the optical drive and wait until it mounts on the Desktop. Select Go to Folder from the Finder's Go menu. Enter /Volumes/Mac OS X Install DVD/System/ and click on the Go button. Navigate into the Installations folder to find the packages. You will need to look in one of several packages: Essentials.pkg and AdditionalEssentials.pkg. If you deleted the preference pane then you will need to look in the /System/Library/PreferencePanes/ folder within the package after it's loaded into Pacifist. If you deleted the application then look in the Applications folder.
After restoring the application you need to reinstall the OS X Combo Updater for the version of OS X you currently have installed. This assures the new copy of the application is updated to the current version.
Lastly, it's a good idea to repair permissions.
