First of all give us some more information about your machine.
The output of lspci from terminal would be useful.
Are you using PulseAudio?
Can you make a screenshot of the alsaconf window right after boot? (when you have no sound)
Yep... more data is better than less.
Motherboard vendor, model, and in some cases, revision can all have an effect on the solution.
Which 2013 is it? (KDE4, LXDE, XFCE, etc., or a combination environment? Example: I run KDE4 but use
LXDE as my primary environment.)
Do you have more than one sound card
available in the system?
(That is, you're using the one on the motherboard, but is there another in the card cage somewhere?)
Definitely include the info agmg has asked for, too. Let's work the problem.