I got the (!) alongside 51 songs when I upgraded to iTunes 11. I've had this before and managed to locate the songs, but this time they've all vanished. Cant find them using search on my HD. They are mostly tracks not downloaded from iTunes. And i still have them on my iPhone.
Any ideas?
27" imac 2.8Ghz i7 OS 10.8.2.
That is not a itunes problem, itunes won't delete songs unless you told it to do so.
Something else might have happened, corrupt filesystem could be one of the reason or you yourself might have done something.
What you can do is this,first check how many songs you have in iTunes after this close iTunes and go to /Users/your name/Music, rename the itunes folder to iTunes old then open iTunes and first thing to do is go into iTunes Preferences and in the advanced tab uncheck the two top boxes(copy to itunes and keep organized.
Now, drop your music on itunes and look if they are there.
Also compare how many songs you have now.
If all is done go back to /Users/your name/Music and delete the iTunes folder and rename the iTunes Old back to iTunes.