Problem with league of legends not starting

So I was gonna go play some urf with my friends and I did, after some games, I was gonna go do something, forgot what I was gonna do. When I came back my league just crashed and when I tried to start it up, it didn't wanna start up the ehh place where you login.

Is there a way I can put a picture in my post? I can't seem to figure out how

Edit : it's only on my pc it doesn't start up, it works fine on my mac though. (I have tried uninstalling and installing again, still doesn't fix the problem)