Can Windows Explorer read the folders and files?
If so, you can copy them into your Windows 8.1 system.
If the Windows 10 DVD is an actual image of your Windows 10 system created using imaging software, then I would assume you can use it to restore Windows 10.
However, you should be upgrading to Windows 10. You cannot run both Windows 8.1 and the Windows 10 you upgraded to at the same time. It's one or the other.
Since you reverted back to Windows 8.1, my advice is to re-upgrade to Windows 10 when you're ready to do so.
Regards. . .
jcgriff2