hola alguien me puede ayudar

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Warning: main(): Failed opening 'language/lang-.php' for inclusion (include_path='.') in /home/webcindario/contactoslleida/mainfile.php on line 189

Warning: head(themes//theme.php): failed to open stream: No such file or directory in /home/webcindario/contactoslleida/header.php on line 31

Warning: head(): Failed opening 'themes//theme.php' for inclusion (include_path='.') in /home/webcindario/contactoslleida/header.php on line 31

Fatal error: Unknown function: themeheader() in /home/webcindario/contactoslleida/header.php on line 47

que puedo hacer