MP3 player doesn't read chapter names

The MP3 player shows every chapter as the name of the book.
It shows Title of Book : <- there is nothing after the colon.

So the chapters play in what sounds like random order not chronologically. So it does not read the number and does not show the chapter title. MP3TAG shows that the chapter names are there.

Is there anything I can do in MP3TAG to make the MP3 Player see the number of the track (chapter) and/or the Chapter titles?

What kind of file format are we talking about?
MP3? M4a?
To get the best representation of an album, fill the tag fields
Preferably all files should have the same data for ALBUMARTIST.
ALBUM should also be the same for all files.

The field TITLE should also be filled. If there are not real names for the individual tracks/chapters, then create a dummy one that consists of the data from ALBUM and TRACK.
This is easily done with the function Convert>Tag-Tag, provided the tag fields ALBUM and TRACK are filled.
Select all files of the book.
Open Convert>Tag-Tag
Select field TITLE
Enter as
Format string: %album% - $num(%track%,3)

I apologize for being ignorant (and maybe retarded) about the terminology for these fields and commands. For example, most the answer is beyond me.

My focus is on an MP3 audio bought from Tantor Media. Half of the chapters did not have the chapter titles but only the name of the book. I used MP3Tag to correct the titles. Hurray for MP3Tag.

The problem is that My MP3 Player still shows all the Chapters as the name of the book. What is the Player seeing and can I use MP3Tag to change it so ihe Player reads the Chapter names which are there?

If MP3tag already shows the changes then it is hard to say how to get the player to show them, too - if that player does not detect the changes.
So try to find out how the player updated its information, perform the update and see what the player shows now.
Sometimes it is worth a try to rename the files just a little bit (with e.g. an added underscore at the end) so that the player sees the files as new files and then rereads the tags.
If that does not help, it could be that the player does not read the tags but relies on the filename, I don't know.

When you say that

then please tell us where you have the difficulties. Otherwise it is difficult to help you.