depends on what you mean by "deleted."

If you just cleared a download entry on LW's search page, you can resume the file from the LW LIbrary page (click on the incomplete folder to see a list of files you can try to resume).

If you stopped sharing a folder and it doesn't show up in LW's Library pane, you can just add the folder back again using the Library's File menu.

If you used the delete button in the Library--sorry: those files are gone.

If you used your Operating System's delete/trash/recycle (or whatever it's called), only special tools can *maybe* recover the file.