FPS DROPS

Please help me, my pc isnt that bad but it runs league at 60-70 fps, but yesterday it started going down , like from 60-70 to max 25 i tried everything, from reinstalling league to 'initiate full repair' but its still the same the problem isnt from my pc, because many other games such as Naruto shippuden ultimate ninja storm 3 and rocket league run at 50 fps (thats how they were runing before league fps dropped) i thought i'd start this discussion so someone could help me*[zombie-nunu-tears]*

EDIT: i think its a file coruption thing , idk how it works but i think of that because the (i think) new? trophy statue in the map is all white. sometimes all blue with no texture or anything