I have crafted several level 70 purple stims for my guild but we don't use them all. If anyone would like a stim I am on the Jedi Covenant server, my IGN is Lithp.
Depends on what you mean by "can't get the quest back." If it just completed and you missed the cut scene it should be a simple reset quest in your log. If it is actually gone then you will need to contact customer support as the others have said.