Check the speaker icon on the task bar to see if it has a red slash across it, this is the Mute indicator. Right click on the speaker icon and click on Open volume Mixer and see if one of the sliders is set for minimum. If everything is normal, then open Device Manager and open the audio device for your laptop, right click and select Uninstall and click the check box to delete the driver, and then click on Action at top and select Scan For Hardware Changes and this will force Windows to install a new set of drivers.