I'm the a sound expert but I'll share with you what worked for me.
Open the mixer and raise up the PCM & Master.
Add yourself to the audio group log out and log back in again. (adduser yourname audio)
If that doesn't help--
Open the terminal and run:
You'll see a black/grey background with multiple columns. Taise all colums all the way up mute and un-mute each column.
Do a sound test which is file noise.wav.
 at the bottom of the column means un-muted-
[mm] at the bottom of the colum mean muted-
Make sure that you have th Linux Sound Architecture Driver-
Files that are associated with sound that you can look at:
After I adjusted all of those columns it worked for me; Hope it does for you as well-