Just to confirm the device is working, right click on the device in device manager and click properties - it should say the device is working properly.
Next open the Volume Control and click on Options then Properties and your realtek should be shown as the mixer device, click the drop down arrow and see if there are other devices there, let us know the list of devices that it shows.
You can try reinstalling the driver from scratch. Make sure that first you download the up-to-date driver for your laptop from your manufacturers website. If it is a zipped file extract the contents to a folder and remember where that folder is. Check you have the instructions for installing the device driver.
Then right click on the device in the device manager and select uninstall. Reboot the laptop and follow the instructions for installing the device driver. If all goes well robert should be your mothers brother.