how can i point a torrent to a completed file?

[shaftz0r]

2 examples

1- i have a completed torrent, but not the actual torrent file (say i deleted from my hdd and utorrent). if i download the origional torrent file how can i point it to the completed file

2- have the torrent itself, but need to move the file itself.

 

both are the same question in theory, just different scenarios. ive been trying to figure this out for a while now.