I downloaded the Special Edition of 'Avatar' with the included 'Extras'... I use to see them in my iTunes library, but, can no longer locate them anywhere on my computer or in the iTunes library files! What happened?

Question

I purchased 'Avatar' The Special Edition with the included Extras with a gift card. I had enough money in my account to cover this purchase. I only got to watch the 'Extras' for one or two times, and now, they have vanished! They no longer appear in my iTunes library or anywhere on my computer! Where are they and how do I regain access? The movie, itself, is still in the library...only the downloaded 'Extras' are gone!

Answer 1

Visibility of the Podcasts section is controlled from within the Edit > Preferences dialog.
Empty/corrupt library after upgrade/crash
Hopefully it's not been too long since you last upgraded iTunes, in fact if you get an empty/incomplete library immediately after upgrading then with the following steps you shouldn't lose a thing or need to do any further housekeeping. In the Previous iTunes Libraries folder should be a number of dated iTunes Library files. Take the most recent of these and copy it into the iTunes folder. Rename iTunes Library.itl as iTunes Library (Corrupt).itl and then rename the restored file as iTunes Library.itl. Start iTunes. Should all be good, bar any recent additions to or deletions from your library.
See iTunes Folder Watch for a tool to catch up with any changes since the backup file was created.
Missing tracks
Typically this can happen because a file or folder is accidentally shunted to the wrong location. iTunes can also get confused if it expects to be talking to an external drive which isn't there. If will often reset the default media folder location and may have trouble finding files in the old folders.
Select one of your tracks that is missing in action. Press CTRL-I to Get Info. Cancel when asked to try to locate the file, then look at the location given on the summary tab. This where iTunes thinks the file ought to be? Now find out where it actually is. Post back the two locations for comparison. I should be able to give you some steps to reconnect everything once I can determine which of the things that might have gone wrong is most likely in your case.
When you get it all working make a backup!
tt2