Loops library missing

There are lots of popssible reasons why they might vanish.. depending on what you did/change either in logic itself or in OS X..

First things first though....Make sure you haven't accidentally turned on any filters in the Loops Browser...

Set up the browser as shown in this screenshot and check...

In that case, follow the advice given here..

http://support.apple.com/kb/HT3443

If this doesn't work you can try rebuilding the index in Garageband... (if you ahve it installed) as for some reason this workaround often fixes the problem you are having.

Failing all this, you can simply redownload and install both the essential and additional content including all the Apple Loops via this external link..

http://dl.dropboxusercontent.com/u/2972851/logic-downloads-fixed.html

As for why this has occured is hard to say unless you give us much more info like.. Did you change something/rename something on your system HD/install something... just prior to the loops vanishing...