the problem is solved and very simple and corny by the command: yum reinstall clearos*

You then need to do something in the webconfig before anything appears (depending on which screen you're in as some screens such as the IP Settings screen contain a continual refresh). That is why I said to refresh your screen after touching the file.

There is no file with this name /var/log/webconfig/debug.log
/ etc / clearos-release in the directory is
touch /etc/clearos/webconfig.debug - executed the command, the webconfig.debug file appeared, but it is empty

It looks like you are running 6.x. Are you aware that it went end of life in 2019 and has had no updates since them?

To debug further, try to enable webconfig debugging:

touch /etc/clearos/webconfig.debug

Then refresh the screen. Disable debugging again by deleting /etc/clearos/webconfig.debug then have a look in /var/log/webconfig/debug.log and you should see some errors (there are always a few, but there should be something relevant to this problem).

[edit]
Guessing, but does the file /etc/clearos-release exist?
[/edit]