Cooment form has vanished from all pages

Dear HD,

I use Virtue 2.3 theme. In the beginning it provides comment form on every new entry – page, note or portpholio.
After a while, the forms from all pages has disapeared. I checked page settings and general settings – allow flag is ON.

The comment form only remains on NOTE type entries.

TIA, Mikhail

And more, if I chage the theme to another, the comments on pages appears again.