Dolby is a technology embedded into laptops, therefore the manufacturer of you laptop needs to be reached through the Support channels. Basically, you have to visit the Support section of your manufacturer's website to download and check for drivers. Do no try to install 3rd party drivers or anything from other websites. Dolby is problematic and you'll end up reinstalling the OS because of the problems caused by wrong drivers.
The model of your laptop is listed on the sticker next to touchpad or on the back of the laptop.