Why aren't mp3 files I deleted by accident showing up in the Trash?
Yes I do, is there a command to move them to another folder? In the short term I don't mind where they are, as long as they're not sitting in the trash waiting to get deleted! 


Answering down here to have enough room.


Create a new folder to move all these files from the Trash into. It can be anything, for this example I'll create a folder called "undeleted" on the Desktop.
Open up a Terminal window, and navigate to the Trash: cd ~/.Trash.
Confirm that the stuff you want is there: ls -a.
Move the mp3s: mv *.mp3 ~/Desktop/undeleted. If you create a different folder somewhere else, the easiest way to get its path is to drag it into the Terminal window. Type in mv *.mp3  including the trailing space, then drag the folder you want the files to go into into the window - it'll automatically fill in the correct path. The * wildcard will match any .mp3 it finds.
If you have any AAC encoded songs, repeat the above, but change the extension to .m4a: mv *.m4a ~/Desktop/undeleted