I'm going to assume that you're not getting any sound at all.
First, check the volume icon by your clock. Make sure it's not muted, or turned down too low.
Then, check the control panel-->sounds and audio devices-->audio tab-->make sure you have a sound playback device selected. If you can't, you need to reinstall the audio driver. You can go to the laptop manufacturer's website, search for your model, pick your operating system, download the audio driver, and then install it.
If those don't solve the issue, let us know and we can go from there.