not letting me play

so i played and finished a game and it went well as i played yasuo , and before that game my league of legends was kinda lagging. so after the game i went back to home screen and then, my league of legends started to be glitchy so i tried to log off, as i loged back in it said that i disbanded a game or my game crashed when i clearly finished it. So now it said i have to reconnect, as i tried to reconnect the screen was black so, and i tried to do everything i tried restarting my pc, shutting it down and everything else. so now i cant play games or do anything on league of legends and it has made me very upset*[zombie-nunu-tears]* and i have check my pc and there is nothing wrong with it.

thank you