Are the speakers muted? Look down by the clock for the speaker icon:
If it has a red mark like this image:
it means that it is muted. If this is the case, double click on the speaker icon and uncheck the mute option. Many keyboards also have a mute button and if yours is a multimedia keyboard, that is likely how the mute was set.
If this isn't the problem, then it could be that your speakers are "enhanced" which just means that they need AC electrical power to run. Check that they are plugged in and receiving power. There is often a power light that shows when the speakers are properly powered.
If nothing here helps, it may be a problem with your audio card. You can run a sound test using the DirectX Diagnostic utility tool.
1) Click Start
2) Click Run
3) Type in:
dxdiag
4) Click OK
OK the "Check for WHQL dialog if prompted
Run the sound tests. Sometime you can hear some sounds, but not others. If you hear some but not all of the sounds, you may need to reinstall the audio sound card driver.
In the DXDIAG utility, click on More Help, then on sound. Go through the Wizard and see if any of the listed items helps.
I hope this will solve the audio problem. If not please post again and report what you've seen and done.
If I may, a personal note. I have responded to a number of posts by you and I do not recall your ever responding (forgive me if I have forgotten).
I'm not sure if my responses are helping you at all, or if you're even reading them. It is most helpful to us if you post a reply and let us know if our advice is helping you at all. We are here because we want to help, but it is very discouraging to never see a reply letting us if it did in fact help.