@ Esmi : would it be really bad, in the process, to update an old WP to an up to date one ? That would be killing two birds with one stone...
@ Cleanimage :
- if you must reinstall the same wordpress, you can find WP 3.0.1 (search for "3.0.1" on that page) here : http://wordpress.org/download/release-archive/
You may wait for Esmi's opinion (I didn't think of WP versions, see, that's a pro for you !), my opinion is simply : unpack it, upload it and allow overwriting.
- regarding backups, the reference is :
http://codex.wordpress.org/WordPress_Backups
. For the database, this is not something you can access or retrieve with your FTP client, it's stored elsewhere. I'm now backing it up with wordpress plugins, and on rare occasions with my web hosting panel. In your case, see if you can back it up within your web hosting panel too ? Or otherwise, you may have a phpmyadmin access ? if so, login with your database credentials, click your DB name if it's not auto-selected, click the Export tab, select "all tables", and just tick one last option, to save your db as .zip or .tar.gz
. for the files, you can simply log in by FTP, select everything starting from the root of your blog's folder, and save it somewhere on your hard disk.
. This way, with both files and database saved, you're safe, even if you totally screw up the wordpress fixing, you can restore everything back easily :)