Go to Library window, at bottom of window you will see Incomplete folder, click it open. Then select all (hold down shift key), then press Resume button. This will force them back into the download window. They will all show zero percentage downloaded until they actually start downloading again upon which time their previous download % will show.

It gives the impression your LW is not shutting down properly after closing it at end of a session. Make sure LW is set to close immediately in settings. Wait a few mins at least before shutting down computer.

If you have a large number of incomplete files, then it would be well worth doing this: Tip: Purge the Downloads Queue! (click on blue link). It will help get rid of the possibility of any fakes you accidentally downloaded which can cause LW havoc.