No they wont play once they have been deleted from your LW library, even though they are still listed in itunes...Their gone....
The best advice I can give is to use one of the recovery programs the guys have listed above....Good luck I hope you get them back...:rolleyes_2:

Hey ffthorne, Just for future refrence If you upgrade to 4.13 beta everything that is deleted will now go to the recycle bin so you will have a chance to recover what gets deleted. Dude I would have to delete that girlfriend!!! Good Luck

Also, if you add the songs to iTunes Music Library then you won't need to worry about deletion of songs. Whatever you do, don't think that just because you see a LW playlist within iTunes that the songs have been added to the iTunes library. The LW playlist is simply a playlist which reflects what songs you have in your LW download folder. So ignore the LW playlist in iTUnes. To add songs to iTunes Music Library, see How to transfer music to my iPod (& iTunes). You will notice there are many techniques to add songs from LW to iTunes music library. ;) :)