no sound

Im having a strange issue...this just recently strarted to happen....im the the screen right after where you can login in and everything like where you can buy things with IP or RP...well no sounds will occur when i press on anything...same with champ select...i have tried messing with the setting and making sure my headphones work, my sounds on, and thay league's sound is on but nothing is happening. if you ccould look at this somehow that would be great... thanks :)