Most of my Icons disappeared from the Sidebar !! To Restore I just had to hover the Mouse Cursor over the top right of the Sidebar, and click "Show" Which set me thinking, can I have coloured Icons in the Sidebar again, which went monochrome a few updates ago, after 10.6.8. I found this software, which works a treat under Mavericks. SideEffects puts colour back in the OS X 10.7, 10.8, and 10.9 Finder sidebar.