Need Help on Fatal error (include_path='.:/opt/ - Joomla! Forum - community, help and support

hello have installed joomla @ first time  , everthing goes right,

the website working fine 1 day  afther backend changes receive error

fatal error: main(): failed opening required '' (include_path='.:/opt/php/lib/php') in /home/www/a8406aa3b2ca495f477b7c7bba328b86/web/administrator/components/com_messages/admin.messages.php on line 19



somebody can me resolve problem?
possible backup contents, users,,,, before reinstalling, or settings stored on mysql???

many thanks  implent joomla on several domains if running stable.

have done changes on operating system running on? looks trying load library can't find.

all settings , content stored in database, exception configuration.php.