First, the speaker inside the membrane is broken, can go to the repair point, not very expensive! 　　

Second, speaker short circuit, contact bad, want to open the line to the prison, but also may be caused by dust, clean the dust directly! 　　

Third, the speaker is bad, you want to change the speaker, should also not be very expensive!! 　　

Fourth, check that the sound card driver is unloaded, 　　

In my computer properties of the hardware in the device manager to see, reinstall the sound card driver, after the restart try.