head of the winter wolf not dropping/gone?

Hi, after a bit of time of playing the game I noticed that few bosses can give permanent stat increases, so I went back to the first "boss" and figured it would drop there. after killing her about 20 times I started thinking something was wrong or that the drop rate was just super low. Until I found out it is suppose to drop on the first time u kill it. I have no idea if it ever dropped the first time I killed her, or if I have somehow missed picking it up, or sold it by mistake. But I don't have it in any stash folder, nor can I find it in any buyback shop.
Is there a way to fix(please fix) it without having to restart a character?
Losing a permanent stat increase like 10% cold resistance is Kinda major.