A single complete guide is a bit of a stretch. There are too many facets to Linux (or Windows or MacOS for that matter) to fit everything into one book, however fat that book may be.
You can start at
The Linux Documentation Project. Much of the stuff there is older, but, as it tends to be command line-oriented, it's still quite valid. My go-to reference when I started with Linux was Garrels's Introduction to Linux. I still have a copy on my bookshelf.
You can also find a wealth of books as
O'Reilly. Much of the older stuff is available for download, but you may have to hunt around to find it.
You should also learn how to use the man pages. Note that they are not designed as tutorials, but as references. Enter this command in a terminal to learn more:
As regards the DVD issue you mentioned, it would be helpful to know whether the DVD is a commercial DVD with DRM and whether it's NTSC or PAL, as well as what program you are trying to open it in. Furthermore, generally, if you want to play a DVD or an audio CD, you don't "mount" it as a file system the way you "mount" a USD stick'; you open it directly into a media player.
Also, if you have a DVD player, test the disc in it to verify that the disc is indeed readable, if you have not already done so.
I will suggest that, if you have not tried to open the disc in
VLC, give that a whirl; generally, if it won't play in VLC, it won't play in Linux. I would expect VLC to be in the Zorin repos.
