Champion select not showing champions| going back to lobby/homescreen when i accept a game, crashing

Hey guys, so recently my champion select has made it so i cant play 99.9% of my games; Whenever i accept a game, it takes me back to the lobby/homescreen even though i can hear the music. When im lucky enough to get to champion select, i dont see the champions most of the time. Sometimes my client even crashes. I then have to wait a time penalty for something that isnt my fault. Please help. Kind regards Btw congratz on s5, really fun.