I've had this problem with Raeltek too.
Here's how to fix it:
Go to Control Panel, then Device Manager. After doing that find Sound, Video and Game Controllers in the device manager, click on that, then when the subcategories open up, right click on Realtek HD Audio, then disable it and enable it again.
This will work untill the next time you start up your computer/ laptop, and then you have to do it again.
If that doesn't work, try to uninstall the driver and then install it again.
