Well, Depending on your knowledge of computers, You have two options. 1: Crack open the case and inspect the connections from the motherboard FP Audio header to the front headphone jack. 2: Take it to a shop and have them look at it for you.
If you've recently updated the drivers, You could roll-back the original drivers in an attempt to fix the problem. Simply right-click "My Computer", Click Properties, (Assuming you're running Windows XP) Click the Hardware tab, and open Device Manager. Right-Click your audio device from the "Sound, Video, and Game Controllers" list, And click Properties. Click "Roll back Driver".