It is possible that the internal speakers have gone bad. First follow some steps given here at http://www.askiyogi.com/hardware-peripherals-drivers/15628.html which is given below If this does not help, run the internal diagnostic test on the speakers. Reset the BIOS to defaults.
(a) Download the latest sound drivers compatible with Windows 7 from the system manufacturers website and install it.
(b) Right-click the volume icon, select Playback devices, go to the device you wish to set as default (your speakers), right-click it, and select Set as Default Device.
(c) Make sure the speakers are connecting to the correct output port.
(d) Check the default volume level and sound enabling in the game settings.
(e) Check the default audio output configuration of the player you are using.
(f) Check if audio comes out from other application, if yes, reinstall the game.
Here’s to Good Karma