Accidentally discarded quest item?

I took a quest and some items were put in my inventory but i did not know that these were my quest items nor did it tell me. I looked at the items and discarded them, then it told me that those are my quest items which i cant deliver now. It told me that I can find the items to replace them, but they are not in the trade terminal. The item is the de-scented pheromone bottle.