I am guessing this is a Torrent file? For torrents I'd recommend either using uTorrent or Vuse. I know Vuse has a data check option which overcomes issues like that. I recently had to use it & it discovered it had in fact downloaded most of the file & re-adjusted the download %. Unlike LW which has no such option. The option in Vuse also works well if your computer crashes or the program is not shut down properly. In such cases Vuse will *auto* re-data check the actual file content to see how much was previously downloaded. Again, if LW crashes in similar fashion, there is no such recovery tool. If LW's downloads.dat file becomes corrupted, you are stuffed.

Whilst LW has some improved Torrent features, it's situations like yours that particularly lets it down. I am not sure I would trust LW to download a 60 or 100+ GB torrent file.