This thread is resolved. Here is a description of the problem and solution.
Content (pages, posts) are missing on admin dashboard after installing/activating WPML plugin.
uninstalling WPML completely and re-installing WPML resolves the issue.
-backup your site completely (important!)
-reset WPML by Going to WPML >> Support >> Troubleshooting >> There, click on “Reset and deactivate WPML” - this action will remove WPML tables (tables with the 'icl_' prefix) from the database.
-deactivate/delete all WPML plugin
-deactivate all non-WPML plugins
-download a fresh copy of WPML plugin from your wpml.org account.
-install/activate WPML plugin
This is the technical support forum for WPML - the multilingual WordPress plugin.