I downloaded a file i've been trying to find for a long time and i have misplaced it, and now i cannot remember what it's called! is there a log somewhere that'll contain all my completed downloads listed or anything like that?

Thanks.

No Log unless you specifically request it. Normally for under Help -> Diagnostics.

If you have trouble with it, you can filter, for a part of the transfer name.
Also if you go to Layout -> Select columns I find that "time added" "time completed" and "Last Activity" work well when I'm in different categories or STATUS and need to re-seed old transfers. Or to pop on and see if anyone needs. Last Activity unfortunately doesn't work for dead torrent swarms. When downloading, the last peer that sent you data is stored. When seeding, the last time you sent data. So if a swarm is dead, use another metric, for ex: cycle all "A-F" on Monday, "G-L" on Tuesday, etc