in the settings/system/sound menu, does Realtek show twice in the drop down for output device? Perhaps try the troubleshoot option under volume slider on same page
can you right click start
choose run...
type dxdiag and press enter
it might seem odd to go into directx but it also shows details about audio in here
can you click on Save all info on System tab
this opens file explorer and lets you save data as a text file. Can you do so and upload it to a file sharing site and show link here, might give us more of an idea of how to fix this for you.