Windows DVD Player.
The Windows DVD Player app is available free for a limited time for people running Windows 7 Home Premium, Professional, Ultimate, Windows 8, or Windows 8.1 with Windows Media Center.
Please note that Windows Media Center isn't included in Windows 10 and will be removed when you upgrade to Windows 10.
After the upgrade completes, Windows DVD Player will download automatically to your PC.
To be eligible for the free DVD Player app, you must upgrade your Windows 7, Windows 8, or Windows 8.1 PC rather than perform a clean installation. If you’re running an edition of Windows 7 or Windows 8 that doesn’t include Media Center and you upgrade to Windows 10, go to Windows Store to buy Windows DVD Player or another app that plays DVDs. Provided your PC has an optical disc drive, Windows DVD Player will play DVD movies (but not Blu‑ray Discs).
For more info, see Windows DVD Player Q&A.
VLC media player for Windows 10.
Download VLC media player from VideoLan, once it’s installed, open the program. Assuming you have your DVD inserted, click on Media > Open Disc then just sit back and enjoy your DVDs.