Update Sound Driver - No Sound

I have no sound on my computer but when I use headphones, I hear sound so I am thinking there is something wrong with my sound card or drive so I want to update the sound driver but not sure how to go about it. Can anyone help me? Right now I think my sound card or driver is Vinyl Ac97

Is the sound integrated on the system board or is it provided by an add-on PCI card. Provide the make and model number of the computer and I can help you locate the right driver. If this is a custom built computer, then provide the make and model number of the system board if it's an integrated sound device or the make and model number if a PCI card.

Since you hear sound through the headphones i suspect either a faulty speaker connection or maybe even the speakers themselves. Have you tried another set of speakers or tried yours on another system?
Are they powered or not?
Recheck the speaker connection.
OK then I need to see what the Audio Properties show as your default audio device.
Go to Start and then to Control Panel
Right click on the Sound or Audio Devices and then click on Properties
At the top of the window click on Audio and what does it say for Default Audio Device?
Click on Playback and same information?

Also:
Check speaker connection to back of system
Check volume control in windows by doing the following:
Go to Start and The Run
Type in sndvol32.exe and press Enter
Make sure Master Volume is not muted and turned up
Check Cd Player volume is not muted and turned up