Sound only left side but.....

With Windows 8 , I have the following problem.

The sound on my laptop seems to come only from the left side.
BUT once I plugin my head phones and unplug them, then the sound it good for both sides???

I am so confused... any thoughts?

You have a bad/dirty headphone jack. Plug in the headset plug, in and out several times to see if that corrects it. There are extra contacts in the jack to route the sound and one of the contacts is "dirty". Plugging in and out several times, in many cases, will fix it.

If not, it will have to be serviced.

I used to do guitar amp repair, and saw similar jack problems in guitar amps frequently,.

Thanks.. will that also be the case that when I take it out of sleeping mode, then I have to do the same thing.
in order to make the sound work

Could very well be the case. It appears to be a "mechanical" problem with the jack.

With your headphones plugged in, right click Speaker icon on task bar>Playback devices>highlight Speakers>Properties>Levels tab>Audio output/Balance; do the same with Headphones.