Launcher freezes and crashes after 5.6 update

So two days ago, I update LoL for patch 5.6, it worked well for it. But now, When I open, the LoL icon appears like usual, but it stays there. Then after 20 or so minutes I get pop-up saying that I froze or that it crashed. So I close it, but it stays there with a white rectangle behind it. I have to restart my computer only to get it perfectly fine. I tried deleting LoL so that I can download it a new. But it takes forever to delete it, and a pop-up appears saying I have it opened.

Did anyone have a problem similar to mine? If yes, please tell what's the problem and how to resolve it.

Thanks