My iTunes Media Folder Has Disappeared With 12,000 Songs

I have a library of local music files, organized in my iTunes Media folder, on my MacBook Pro. It's about 12,000 files, totaling 66 gigs. The folder has disappeared. None of the music files that it contained appear to be on my hard drive, and can't be found via a Finder or Spotlight search. The iTunes Music Library still shows the songs, but they can't be played and I get a "file could not be found" error.

I recently cleared the caches for the system and all users using Cocktail. I also deleted several movies and TV shows from my library via the TV app. Those are the only actions I've recently taken that I could possibly imagine might result in such a disappearance.

When I select a song via the iTunes music library and click on "Get Info" to see where the original file is located, I get a "The song 'SONGNAME' could not be used because the original file could not be found. Would you like to locate it?" message. When I click "No," the information pane for the song displays. Under the "File" tab, all the songs show this file path: "file:///Users/UserName/Music/iTunes/iTunes Media/iTunes Music/artist name/album name/songname.mp3." But there is no longer an iTunes Media folder in the iTunes folder in that filepath. I have a Music folder, and within that folder is an iTunes folder. But there is no iTunes Media folder or iTunes Music folder inside it. The iTunes folder contains an Album Artwork folder, a Mobile Applications folder, a Previous iTunes Libraries folder, and various iTunes Library xml and itl files.

When I use Finder or Spotlight to search for the files by name, they do not appear. Searching for file names of songs that are in the iTunes library turns up nothing. When I use Finder to search for all files where "Kind" is "Music," none of the songs in my iTunes Library turn up. They are all completely missing. The files are not in the Trash.

Does anyone have any idea what may have happened?