Microsoft has removed the ability to play DVDs from Windows Media Player as part of the Windows 10 Feature Deprecation.  Instead, Microsoft has made a separate Windows Store App for Windows DVD Player, available for purchase at the current price of $14.99.  This app does not currently play Blu-ray discs.

A free alternative DVD player is VLC Media Player, which is available for Windows, Mac, iOS, Android, and Linux. It is an open source product developed by VideoLAN, a non-profit organization made up of volunteers.  VLC does not specify playback of Blu-ray discs, although VideoLAN does have LibBluRay available.