Sound card inside the laptop has occurred problem, try to reinstall the audio driver or update it.But firstly uninstall..how?

To uninstall and reinstall drivers in Windows 7, perform the following steps:

• Click the Windows icon in your taskbar, type device manager in the Start Search box, and then press Enter
• Double-click on Sound, video, and game controllers
• Locate and double-click the driver that is causing the error
• Click the Driver tab
• Click Uninstall

TO UPDATE THE DRIVER

1. Connect to the Internet.
2. Click Start , and type device manager into the Start Search field. …
3. Double-click Sound, video and game controllers. …
4. Right-click the name of the audio device listed under Sound, video and game controllers.
5. Select Update Driver Software.

If you do not hear sound coming from the laptop, first check if the sound is muted or set to low on the laptop and application. If this is not the case, your speakers may be blown out.You may need to take it to the customer service center.

Hope this helps.