If you have left the downloaded data in the same place (directory and/or drive) and use µTorrent, you could copy the content of %AppData%/utorrent from your old installation to the new. The other way is the reseed procedure: For µTorrent/BitTorrent look there > https://community.gaytor.rent/index.php?topic=6539.0 or generally: https://www.gaytor.rent/faq.php?lan=1#505