Quest Fear This

Hello,i have a problem with the quest "Fear This".
I got to the point were it says get some poison sacks from some mobs,i got them,went to NPC,got a poison bottle,and then i was supposed to pour it in a waterfall or something.Anyway the bottle looked close to another item that i had at that time and i knew i didn't need it so i accidentally destroyed the bottle.Now if i go to the NPC it opens a a box like a warehouse and i can't get the bottle,so i can't finish the quest.
Any idea what can i do?

 

you can try quitting and if it resets restart the quest
if not then you'll just have to abandon it and move on

 

Hmm thx for the advice but i might found another solution.Make another char make the quest and give main the bottle.
Now here comes my question,are quest items tradeable?
Oo i forgot to mention...it's a campain quest and i don't know how to restart it.