my game crashes every time

I'm not a native english speaker but i hope i can speak everything clearly..

My game keep crashing every game from April 2016, and I went back to my home country during May-Aug. I thought when I come back to U.S, my game won't crash again. But it still crashes every game. After selecting champion, there's nothing on my screen no matter how long I wait. But if I press Command-Option-Esc it will shows that the game has crashed….I'm using a 2012 mac. I have received penalty for 'being placed in a lower priority queue for 20 min'………… I just wonder if there's problem with my hard drive or the LOL itself. T.T