Audio error

[saurabhumkar .]

I have dual booted my HP notebook with Lubuntu 14.04 LTS AMD64 which
comes with the pre installed Windows 8.
Everything is working fine but , i am not able to listen to any audio from PC.
Neither default HP speakers nor my headphones are producing any audio outputs.
When playing a video file in Gnome player i can see the video but
can't listen to the audio.
Please help me out.
Thanx in advance.