I can't hear any sound from my Ubuntu 14.04.4 laptop. I've been using it for a month. Is it because I set the sound output to 'play sound through HDMI speaker'? The fact is, I did connect my laptop to a TV via HDMI port/cable to play a video file from its monitor. After unplugging it, I can't listen anything but the login sound. This keeps happening till now. So far the volume indicator works well, but still no sound appears whatsoever. It's like on mute mode. I've tried my usual media players (Clementine and VLC), their volume indicators work well, yet they give no sound either.
Open System Settings and under Hardware click the Sound icon -> select the Output tab. Check that you have Analog Output Built-in Audio selected as in the below screenshot.
You can click the Test Sound button at the bottom of the Sound window to check if you hear any sound from the left and right speakers.