So basically my Joomla site was attacked a few weeks ago by SQL injection and was taken down.
What I am hoping to do, is to go into the file manager and download all of my articles, categories, menus and templates, then set up a new joomla site and upload all the old code.
I am just wondering is this possible as I do not want to have to recreate the entire site again.
Any help would be much appreciated.
You won't find anything like articles, categories and menus in file manager. You should be able to find the Joomla installation folders and files, including all extensions and media/images files.
Actually what you need to do is to download all these files, plus the database of your site.
Assuming the intruder didn't damage anything crucial in your installation, you should be able to restore your site in your localhost (or other hosting environment) - and then perform all required updates and other security enhancements and finally re-upload your site online.
To restore the site all you need is the original folders/files of the Joomla site instance and the database. You connect the Joomla installation files to the database, through the configuration.php file - it holds variables for the database connection.
These are the configuration variables (with sample string values), referring to the database connection:
public $dbtype = 'mysqli'; public $host = 'localhost'; public $user = 'db_user'; public $password = 'db_user_password'; public $db = 'db_name'; public $dbprefix = 'prefix_';
Assuming you still have admin access, you can probably clean up the website where it is using the commercial https://mysites.guru (formerly myjoomla.com) security tool or similar.
To prevent reinfection, ensure you update Joomla and all third party extensions to the latest versions and reset your Joomla, database and hosting passwords.
See https://joomla.stackexchange.com/a/180/120 for tips on securing the website against future attacks.
You can try this steps.
Install new Jooomla. Be sure was last version.
Import XML genereted from your old site.
You will need create again yours Menus and modules.
But with this steps you are safe with new instalation.
I holpe this helps.