It looks like you were sharing your iTunes music library folders. And the files within are what you have deleted. Either that or you didn't add the song files properly to iTunes in the 1st place; only a reference to them (the LW playlist that shows in iTunes) & thus they were never within your iTunes library but only your LW downld folder. If this was the reason then for the future see How to transfer music to my iPod (& iTunes) about how to get them properly added into your iTunes Music Library folder. Go to iTunes preferences (iTunes menu bar>Edit menu>Preferences>Advanced & make sure Copy to iTunes Music Lib is ticked. If you have iTunes version 5 then it's under Advanced>General.) If you add them to the iTunes music library then you should have 2 copies. The other in the LW downld folder. But you need to add them 1st (ignore the LW playlist.) After you add them to iTunes you can delete them from the LW downld folder. Use the LW Library Explore button to open your downld folder when adding to iTunes & deleting once this is done.)

You could always use a file recovery utility such as Norton or get a free one here: PC Inspector File Recovery (click on link) OR if you have windows XP see System restore for deleted files