Hi , Insert your Mac OS X Snow leopard Install DVD into your computer. The disc should appear on your desktop or within your Finder sidebar. Double-click to open the disc contents. Open the Optional installs folder . Step 2Double-click on the Optional Installs package.Step 3Click through the Introduction and License. Select your Macintosh Hard Disk as the installation destination. Click "Ok" and you will be taken to the Installation Type.Step 4Click the arrow next to Applications to unfold a handful of default applications you can install. Select ical by ticking off the corresponding box. Select ical to be installed.Step 5Select "Install" and Apple Mail and any additional software you selected will be reinstalled to your system. Once completed, you may eject the DVD.This should reinstall ical to the default location in Mac HD / Applications. From the applications folder you can drag the ical app back to the Dock for easy access if required. Test . Please let me know if this works for you . Thanks.