My Acer Aspire 4741G laptop sounds suddenly stopped working

Help!!! yesterday it still working but today,no sounds come out from the speaker,I used headset to test it and it's work,but when I unplug my headset it still no sound,I already try to reboot using safe mode but getting confused.. what can I do???
f.y.I : I already check the sound driver,no question marks appeared.

"I already checked the sound driver, no question marks appeared"... Do you mean no exclamation points like this (!)? If you can hear normal sound from the headset the sound driver is okay. This could be caused by a keyboard setting. Make sure the sound is all the way up and that it is not muted

I have checked it too.. no mute at all.. just suddenly no sound when I play game

Does it have sound when playing music or watching a YouTube video?

Nope... I already tried playing music and vidoes.. but still the same...

... But you can hear normal sound using headphones?

Yeah... thats what make me confused... any solution?

When you plug in headphones, the internal laptop speakers are disconnected electrically. This switch contact is in the headphone jack. The headphone jack may be damaged. You can buy laptop external speakers like this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16836121013

Everyone knows... zzz not helping at all.. F.Y.I. it happens before I use headset..

Does your laptop have HDMI output? Did you go and change any of the default settings for HD Sound. What you can do it this. Uninstall the Audio Drivers from the device manager Make sure you download the Audio drivers for your laptop from ACER prior. Simple fix is uninstall the drivers and delete them. Then reboot and Windows will try to install the drivers. But you don't let it you install the Audio Drivers.