When i call someone on BB i cant hear myself and i can hear like little crackels in the background . HELPPPP!?

basically my ping sound is fine buh my friend was listenin to music on my fone and i think she turned something off but i dont know what and when i try to call someone it cant hear myself and the other person cannot hear me at all and their is some sign that flickers into the callin in the left hand corner which has never come up.Before u ask it has nuthing to do with water coz my ping/ camera sounds work fine i jus cant listen to anyfing once i remove my headfones :/// thankyouu :D