It is particularly annoying to find all of your shortcuts, favourites and folder arrangements suddenly wiped out from your Apple Mac Finder Sidebar.
Some people find that turning it off and turning it back on again can reinstate the favourites, or, there is a plus/minus icon beside the favourites title that shows and hides the favourites. Sometimes, this can sort the problem out and sometimes it doesn't lose or forget all of the favourites you've setup.
How to fix missing sidebar in Apple Finer app
The fix, is simply to delete the com.apple.sidebarlists.plist file and then reboot your machine.
In my experience, this option forgets all of your favourites and you have to set them up from scratch, again.
