I would like to start off by saying this happened to me in free to play world, as I am not a member very often, I was training combat, and my friend told me to fight red spiders for some reason I must have gotten attacked by another monster because my combat stats was way lower than it should have been, and I waited and waited to see if it would go back up it took a very long time for it to get back to normal I asked people I know that have maxed in combat and people in a clan that I am part of that said use restore potion as I was told by a lot of people that item used to be a free to play item turned into a members items and there isn't no item that can restore stats other than that, I was then told there is 2 ways to get my stats back to normal become a member to use a restore potion or get killed in game and the stats go back to normal