kmail doesn't show email or headers

[Michael Hirsch]

My dad called me this morning in a panic with this problem and I was
unable to help him.  I hope someone here knows the answer.

He uses kontact and kmail for his email, and has for around 15 years.
I'm pretty sure he's running 16.04, the latest LTS Kubuntu.

He has many mail folders, which he can see fine in kmail.  But
clicking on one does not display the contents at all.  Neither the
headers nor any contents display.

He usually has a 3 panel view with the folders down the left side, the
headers at the top of the right side, and the message contents at the
bottom of the right side.  The panels should have panel dividers in
between the panels.

Now he has only the folders.  Only the single panel with no panel dividers.

Any ideas for where the missing panels are?

I've been trying to find the place that kmail keeps it's settings for
the panel dividers' locations.  If I can reset them then I hope they
will show up.

Where can I find the values of the dividers?

Thanks,

Michael