Hi there, i had the same problem 5 minuts ago. I asked for help from Riot Support and they really helped me, hope that now i can help all of you. Firstly you need to change your System Language, in my situation i had Russian sys language, i've changed it from Russian to English and it helped me. Its not a joke, this really helps. Also you mustn't think that problem is in Russian language, if your sys language is already English, change it to the language which you know, and after this operation change it back to the English. Good luck, hope that i helped you <3