See post by JeffMark77 at:
on how to relink iPhoto library. A similar approach may work for iTunes.
Just emptying iPhoto trash may be sufficient according to:
The problem I'm having is not with items missing in the Event or Project library, but when trying to add music (or photos) - see screenshot. The window where one is supposed to place a piece of music from one's iTunes library (or iPhoto library) is empty.
My iTunes library holds many songs and is in my correct user folder.
I repaired permissions. Also no go.
Of course I can manually place songs in an iMovie project, but it was so much nicer within iMovie.
This is what I understood - your iPhoto and iTunes libraries appear empty when selected from the iMovie 9 - the link to their location is broken. Apparently this can be restored in the case of iPhoto by the procedures described in the articles I referenced. iPhoto must be sending the wrong information to iMovie when it requests the iPhoto library.
OK, now something is weird.
When I try to link iPhoto to my old (real) folder, I can see 2 versions of it (that wasn't there before).
Looking in the finder though I only see one.
Might there be a hidden one?
I opened Terminal and went to that directory, but Terminal also only sees 1 folder called iPhoto Library.
It seems like there is something wrong with the configuration of iPhoto. There is an Apple article on troubleshooting at http://support.apple.com/kb/HT2638?viewlocale=en_US&locale=en_US
There is evidently only one copy of the action photo originals but there may be more than one file that describes its contents and location. The problem with these iLife application libraries is that I've never seen any detailed technical description of exacly how they work. (I don't use iPhoto myself and don't have it installed - I just keep my photos and videos in my own directory and use the Finder for everyhting).
Its the same with iTunes (which I do use) - there is an iTunes Music Library .xml file which if opened with Property List Editor seems to contain all the information about the music items but not the music files themselves which reside in the iTunes Music folder.
I don'tthink I can help any further.
Tried the First Aid options for iPhoto - no change.
It seems to me the problem is somewhere higher in the hierarchy of the iLife structure, since neither iPhoto nor iTunes files can be seen from iMovie.
And since I trashed all iLife apps and their supporting library files and reinstalled everything I'm not sure why this issue is still there.
So annoying, so it seems that no one has ever been able to figure out how to link their iTunes with their iMovie when they encounter this problem. Not that the "help" menu has ever really been helpful, but this makes me question the allegiance to Apple products, when every time I encounter a problem, it is NEVER discussed in the menu, instead all the OBVIOUS processes are described in Big Bird Cookie Monster language, like we're morons. I found this issue dating back as far as 2009 and am still brainstorming different keyword searches in hopes of a good solution, but Apple never got the memo? I guess it doesn't matter if everyone's so devoted to a technology monster just for appearance purposes anyway, I just wish the products and customer service were as cool as they perpetrate!