Login problem

Hi, so yesterday i was still playing without any problems, but for a reason i had to restart my PC and since this moment i cant connect to league again. I start the launcher as usual with my desktop app, it starts and the little login bar completes and then nothing. I get the launcher all black with only the top right buttons options minimize help and close. And then a message appears saying "There was an unexpected error with your login session. Please try again."

Help me out with this pls i still want to enjoy urf while its here !!