audio not working

i am using lenovo g500s notebook. i have a problem with sound. sometime no audio comes from speaker but its comes automatically after restart the laptop... i have up to date drivers.....plz help me out

If this happens while you listen to an Internet Radio, the problem may be with the transmission.

no...i do not use internet radio... it happen automatically .. then i am restart laptop...sound comes for few minutes....then after same problem occur

You need to tell us more about your system, about your current driver for your sound, please fill up the system specs and make sure you have the latest driver for your sound.