no sound in game only

the sound works perfectly fine in the client , i creat a game then champion select (sound is fine ) when i get into the game it just muted i tried almost evry thing i reinstall all to default i checked the sound prefreencs and all i even deleted the file config.d.. in the game folder still same pb , i updated my sound driver still same pb no sound un game only pls help it sucks*[sg-shisa]*