Board Thread:Support Requests - Getting Technical/@comment-4839035-20121230171041/@comment-3335785-20130123121651

Everything can be undeleted is true when it comes to content (eg articles). Files are a different case.

Wikia only keeps the image around for 6 months or so before it is completely deleted from their servers, I assume to save space. Try undeleting a file from around a year ago - it won't.