
Try to reset the computer’s SMC to see if your DVD player can work on Mac or not.
System issue usually after upgrading to Big Sur, Catalina, Mojave, High Sierra, Sierra, EL Capitan, Yosemite, Mavericks, Lion or Mountain Lion. You will need to repair the DVD drive or purchase a new one in order to watch DVD movies on Mac. If your DVD drive is bad or damaged, the DVD player program will not be open.
There are many reasons that cause the issue "the default DVD Player not working on Mac" in macOS Big Sur, Catalina, Mojave, High Sierra, Sierra, EL Capitan, Yosemite, Mavericks, Mountain Lion, Lion, Snow Leopard, Leopard. Possible Reason that Cause Mac DVD Player Not Working Issue
Part 4: Digitize DVD on Your Mac - Leawo DVD Ripper for Mac. Part 3: Solutions to Fix Mac DVD Player Not Playing Issue.