You can try this... It may or may not work... Back up all iTunes music files to disk(s)& also on a separate disk(s) all the iTunes Library Damaged *.itl files (just incase), then deleted everything your computer that is related to itunes or apple. Then reboot your computer and re-download iTunes and install. Then restore music into itunes.....
It’s a iTunes issue, it screws up and loose’s stuff... I read that iTunes has far less issues if you keep all the music in JUST the “My Music” folder not the iTines folder.
Itunes “lost” one of my seasons of SouthPark, luckily they let me download it again since I had just purchased it a couple weeks before
Here is another way that is supposed to work:
1. Quit iTunes.
2. Locate your iTunes folder.
The iTunes folder is stored in
\Documents and Settings\username\My Documents\My Music\
* For Microsoft Windows Vista the iTunes folder is stored in
\Users\username\Music\
3. Open your iTunes folder.
4. Drag the iTunes Music Library.xml to the Desktop
5. Drag the following file from your iTunes folder to the Trash:
*
* Microsoft Windows: "iTunes Library.itl" (in versions of iTunes prior to 4.9 this was called "iTunes 4 Music Library.itl")
6. Open iTunes.
*iTunes creates a new "iTunes Library.itl" and "iTunes Music Library.xml" in your iTunes folder.
7. Close iTunes.
8. Drag the 'new' "iTunes Library.itl" to the Trash.
9. Rename "iTunes Library (Damaged).itl" back to "iTunes Library.itl"