When you plug something into the front does the audio stop coming out elsewhere? If so check its not muted in the windows volume mixer (bottom right hand corner of taskbar click the speaker then click "mixer")
If it doesn't stop the sound coming out elsewhere it could either be a driver issue or it may not be connected, worth checking inside to see if there are cables attached to the rear of the panel.
The audio used to stop coming out of mmy headphones and work with whatever I plugged in but now the audio stays on my earphones and doesn't come out of whatever I plug in :/