Hexhunter is useless Btw. It's worse than a sagitarrian short and much harder to come by even.
2. You unlocked it which means it moved somewhere on the screen. It is still very much on, you just don't see where. You could try 2 things, I don't know if the first will work. You could try turning the enemy interface off and back on in settings. If that doesn't work, only thing you can do is smack something that won't kill you and then click under you so you can stay in combat while you state at the screen and try to find it. As far as I'm aware, it doesn't just move on its own, so you must have Dragged it previously.