All torrents got stopped ?

i was downloading a file of about 801 mb and it was downloaded upto 91 % and suddenly current went and my pc got shutdown because of no electric after about 15 mins when current came back i restarted my pc and started utorrent i saw all torrents were stopped with a crossed sign with an errer message cant open.torrent file so what should i do to start it again. thank you in advance.