Sound Bug

Game goes mute after 1 or 2 matches. The client has sound but once the match starts, there is no sound. All settings are normal, nothing is wrong or changed because I can start up LoL and after 1 or 2 matches or playing like normal, the sound just cuts off. After the match is over and I'm back to the client, BAM!, I got sound again. Start the next match, once it loads no sound. Exiting the game and rejoining the match does nothing. This has been going on since the latest patch. Someone else said they had this problem but they didn't find a fix for it. Don't know if they posted it here either.