Apple's DVD Player won't run (and why is hidden)
It sounds like those discs might be corrupted and therefore might not be able to be read by any application.

However, if you wanted to try one more thing before throwing it away, I would recommend either Handbrake or MakeMKV to "rip" the contents to your hard drive.

If they don't work, I would consider the data lost unless it contains something extremely precious or valuable.