3rd March 2019 - Game doesn't start after champion selection.

So, me and my friend were playing a few days ago and everything was ok. But suddenly his game stop working. It doesn't give out any Crash reports, there are NO POPUPS. He goes to champion Select and Suddenly when the game starts it goes to his Desktop and nothing appears. No black window. Nothing. After champ select , the only openned thing is the client and it doesn't even say reconnect. It happened once, then we looked up for a fix that solved the problem, and we found it. But later, it happened again, we've tried that same Fix and it doesn't do anything now. He sent out a ticket to Riot and they've provided him with a Fix that didn't fix anything. Does anyone have had this problem? Need a fix for it...