Use your computer's search to see if they're still around somewhere. If you're using LW 4.12.6 or earlier, when files are deleted from LW's library, they don't go to the recycle bin first
The 4.13.0 beta version does send files to the recycle bin if they're deleted from LW's library

Have a look through this sticky for file recovery advice
Deleting files from LW library - Don't!! File recovery advice