iTunes Library disappeared

I have a problem with my iTunes. I was updating my mp3 files yesterday when all of a sudden my iTunes Library all files, playlists, podcasts etc disappeared. Nothing was in iTunes at all. Before this happened I was locating music files by clicking on a few marked "!" in iTunes and linking them to the corresponding file in the Music folder. I got an error along the lines of "cannot write Music Folder to disk" and this is when I discovered iTunes had been emptied of all content. I rebooted and the Music Folder was at least accessable but to my horror all my music and related files had gone (2000 or so files). The volume display was up by 8GB an amount that corresponded to the music files now missing.
Any ideas.
Prior to this i had been deleting duplicate mp3 files and tidying up using a program called MusicBox.

Any ideas ?? I am desperate to see if I can find the missing files.
Thanks
Alex

Try going File-> Add to Library and selecting your Music folder in iTunes. If you have folders all over that contain music, you may have to do this for each folder.

No all the mp3's have gone from all visible music folders.
They were gone in a split second, no warning, no system hang.
??

I would try data recovery software, I found

http://www.stellarinfo.com/mac-data-recovery.htm

on my first search, and they do offer a trial version, so maybe give that a shot.