Ice: Shoot the 5 glowing blue gravestones around the map
Lightning: repair the electrical panels around the map, they spark until fixed.
Fire: shoot wind veils around the map. "first one with your back to quick revive should point at you. second one by tank should point the same direction as the first. 3rd one by the box point towards mp40 wallbuy and deadshot and 4th by stamina up should point towards the stairs that lead up from the mp40 wallbuy deadshot area." quoted from Dirtbikemick88
Wind: go to PHD room and press your use key on the book on the floor. The numbers match with the symbols either above them, or below them. Match the numbers with the symbols on the correlating clocks around the map.

引用自 Ragnarok：

Ice: Shoot the 5 glowing blue gravestones around the map
Lightning: repair the electrical panels around the map, they spark until fixed.
Fire: shoot wind veils around the map. "first one with your back to quick revive should point at you. second one by tank should point the same direction as the first. 3rd one by the box point towards mp40 wallbuy and deadshot and 4th by stamina up should point towards the stairs that lead up from the mp40 wallbuy deadshot area." quoted from Dirtbikemick88
Wind: go to PHD room and press your use key on the book on the floor. The numbers match with the symbols either above them, or below them. Match the numbers with the symbols on the correlating clocks around the map.

how do you put them back?

you must buy a weapon then switch to another staff