Problem with searching

Hello, searching tool doesn't work properly on my website. It doesn't find many things in my articles. I've tried to index the smart search, but I get that error: undefined/null. I think that "smart search-content" plugin isn't working well. What could I do?

I send the error picture.

Besides, if I turn off the "smart-search-content" plugin, the indexer error message doesn't appear (but when I search something I don't find many things).

On the other side, in case it could be important about this, when I open and try to save one of my articles (only one specific article), I get that error:

Fatal error: Cannot call abstract method FinderIndexer::toggleTables() in /home/aprende1/public_html/administrator/components/com_finder/helpers/indexer/indexer.php on line 433

This error doesn't appear when I turn off the plugin.

I could send you muy user name and password to check it.

Thank you.

What Joomla! version did you use ? THe error comes from core Joomla! files so it looks like there is something wrong with your installation. Did you try to reinstall Joomla! ?

It's Joomla! 3.1.5. But how can I reinstall Joomla! without losing all my work with the website?

Ok, please firstly show me your site URL and tell me how to reproduce the error.

I've sent you a PM. Thanks.