sound not working in Ubuntu 14-04: suddenly stopped

The sound suddenly stopped working in my Ubuntu, so I googled and followed this link but it doesn’t work to me.

Output of aplay -l:

**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC662 rev1 Analog[ALC662 rev1 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC662 rev1 Digital [ALC662 rev1 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Output of cat /proc/asound/version:

Advanced Linux Sound Architecture Driver Version k3.13.0-24-generic.