I tried something with (neo) sindarin but it's been such a long time since I haven't pratice a bit, that I lost almost everything... I've pretended I could do something right with it, it was just for fun...
Anyway, here's my try:
"Tri i-dur, telitha-le nan i-estel lin."
Which would mean (to me): Through the dark, you will come to your hope
Couldn't find any work for "darkness" and no conditional form, only future...
But really, really, I must say this again: it's just a guessing and I don't have any doubt whatsoever that someone may have a better translation than mine!