FULL GAME CRASH

The entire game crashed. I was unable to click on the screen and my cursour changed to default instead of the riot cursor. I can only assume this means I was out of the window. I tried to close and reopen and even closed the whole client.

I have literally no idea why it happened.

I went into a practice tool game after and its still happening. Please help.

Edit: I was a bit upset so I didn't think to line out my situation. It was mid way through a game as fiddlesticks vs camile. The game crashed after dying when I tabbed out.