Since you posted here, I presume you are talking about FrostClick torrents. Please confirm, and if you are can you tell us one or two FrostClick Torrents you are having problems with. We do not want to know about other torrents individually.
We are finding that sometimes Frostwire 4.21.5 requires a clean install rather than installing over the previous version, and it is not clear if you have done this. If not please completely remove Frostwire, and make a clean install of 4.21.5 (instructions below)
This will, I think, render previous incompletes useless so if you have any in hand complete them first if possible.
Completely remove all traces of Frostwire. To do this use Revo Uninstaller
or a similar program since Windows uninstaller fails to do the job thoroughly. Revo will locate additional related files which need to be removed.
Before doing this ensure you have a back up of the files in your save and shared folders, or at least remove them to your desktop or somewhere similar, just to be on the safe side.
Also remove any .torrent files and incomplete torrent downloads from your incomplete and torrent file folders
Then re-install Frostwire 4.21.5 from the FrostWire.com link above.