Second, check whether the 3.5mm audio jack is inserted on the excuse (desktop computers are generally inserted in the green sound card output jack).
Three, check whether the computer sound card driver has been installed correctly, the lower right corner of the computer's speakers did not chant mute, you can generally insert a headset to try. If the above three points are checked, either your audio cable is damaged, or your portable multimedia stereo is out of the question.