Hi,

Please send us your site admin account by private comment. We would like to have a check.

Please open file site\all\module\custom\md_theme\md_theme.module, add following code to the end of file:

function md_theme_update_7100() {
  db_delete('system')
    ->condition(db_or()
              ->condition('name', 'field_collection', '=')
              ->condition('name', 'md_field_social', '=')
            )
    ->execute();
    return st('Fix bug "User warning: The following module is missing from the file system: ..."');
}

then run update.php.

Also, please remember to clear cache.