Cannot import a deleted song?

New to iTunes, just signed up for Match, and sorting out my music collection.

iTunes found 3 copies of an album, and marked two lots of tracks as duplicates. I deleted these duplicates (including the cloud copies) in an attempt to leave myself with a single copy of the album, but iTunes deleted the whole lot.

Fortunately I still have the actual files, but I cannot for the life of me get them back into my iTunes library. They are in the iTunes folder, I have put them in the "Automatically Add To iTunes" folder, I have dragged them onto the iTunes window, and they stubbornly refuse to appear anywhere in iTunes. I can even right-click the file, play it with iTunes, and add it to a playlist - but it simply will not appear in the library.

Have I somehow marked these tracks as permanently unwanted? How do I fix it so that I can see them in my library again?