before, no$gba played perfectly

, no glitching and the sound was perfect. i have been playing mario and luigi partners in time,phantom hourglass,and many other games but now when ever i load up a rom there is no sound. it worked perfectly two days ago but now i cant get the sound to come up i went to options->emulation setup and sound output mode is "digital stereo" and sound deisred sample rate is in high (44khz)(best). these were the default options so i dont know what has happened.
when i ope he configuration settings it says im using no$gba 2.6 if that helps in anyway
i know its not my speakers. what could it be?