Microsoft killed off DVD playback on Windows 10, instead expecting you to pay $15 for the DVD player app. Yeah, right, we are already fed up with Microsoft. Here is one freebie that is popular to install..
http://www.videolan.org/vlc/index.html
Note that when you upgrade from an older OS to 10, Windows Media Player is supposed to stay and play. I did a clean install, and the above player I linked to does work on my PC.