Rght click on My Computer icon, and select/click on "Manage", next click on Device Manager, next find the Sound Card under sound, video and game controllers, right click, select Properties, and next click on Roll back Driver and wait for the installation to finish... you may be prompted to restart the computer.
If it doesn't work, repeat the procedure and this time select the Sound Card with the right mouse button, and click on Uninstall, and restart the computer... the Plug and Play service should autoinstall on the sound card driver..
If again it doesn't work, go again to the Device Manager > Sound Card and this time right click and select Update driver... and next select "yes, this time only"... the sound card driver should install and if it doesn't repeat the procedure again but this time select the "No, not this time" option and next select the "Install the software automatically (recommended)" option.
If still nothing, repeat the procedure and select from the sound card > Update driver > the Manual driver installation option: No, not this time > next > Install from a list or specific location (advanced), next Don't search, I will choose the driver to install, > and select the driver from "Show compatible Hardware", click next and wait for instructions to restart the computer. Still another option is to unckeck the "Show compatible hardware" box and select another driver manually. If the appropriate driver is not listed, you may need to download it fresh from the manufacturer's website... with your computer make and model, or motherboard make & model if the computer is homebuilt, or with the Sound Card make & model if it's a PCI/PCIe card.