Issue considering game freezing

Hi, riot. There has been a constant game freezing problem that happened to my games, the game is frozen and alt f4 and ctrl alt del dont work. the background music turn into some buzz buzz noise. Only thing I can do is to restart my computer, which is very troublesome and disastrous. I got my computer 2 years ago I think my graphic card is able to handle this, there might be some issues with the client. I noticed that it happened before and I am wondering how may I do to fix it. Thank you.