How to restore a Joomla 2.4 site?

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Outsider V.2015-12-25 22:01:48

Joomla

Outsider V., 2015-12-25 22:01:48

The Joomla site is completely devoured by viruses and inoperable - after deleting infected files, it simply writes a server error (500) when going to the main one.
The engine version was old (2.4, as far as I could find out). I put clean the latest version 2.5.x. Now the question is - how to transfer all the data from the old engine? The database is clear. What else needs to be copied to transfer everything?
Or, on the contrary, can put what is left after removing the viruses, and install 2.5 on top? I really don't know how to...