check in the bios under onboard devices make sure sound card turned on.
look under windows audio control panel make sure the mic not mutted and not turned off in the realtek control panel. under windows audio devices make sure realteck set as default audio output not hdmi. look under device managers make sure under audio there no yellow !!! newest realtech driver is 2.71 on there web page. if there a issue you may have reload intel chipset drivers.