Audio Problem in Laptop Speakers.(redirected)

I have Dell Vostro 3546. Since few days, the speakers of the laptop are not working properly. They were producing scratchy sound but now the sound produced is nil. But when I attach headphones to the laptop but do not select the headphones as the default device, the speakers work perfectly with no aberrations. The speakers work fine then. Please provide solution to this.

Thanks in Advance.