Laptop speakers are no working... but yet they should be?

So I have an old trusty ASUS G1-S laptop that no longer plays sound through its speakers.

The drivers seem to be working properly but I'm not sure what's screwed up. I know the speakers have to be working because my laptop does this funky explosion noise through the speakers upon boot up (it's part of the boot up splash effect), but theres no sound once I'm in windows.

I have everything unmuted, so it can't be something that simple. Sound also works when I plug in a headset or external speakers.

It's annoying because I would like some sound sometimes when I'm in a bit more of a portable situation.

Um... any help? Ask away for details and I'll try my best to supply.

So basically: Sound is working, speakers should be working (I'm pretty sure) but there's no sound from the speakers once in windows.

 

I had the exact same problem with my Asus V1S, it happened after I was using headphones, after I took the headphones out the speakers weren't working.
Something happened to make the computer believe the headphones were still plugged in, had to RMA it, and it was fixed. Unfortunately it happened again after couple of months once warranty ran out, so now I can only listen to sound with headphones or external speakers.

 

There's gotta be some kind of fix for that. Some way to reset it... Someone's gotta have some ideas!