Moving WP site to root

Hi,

I’m a complete newbie here so I apologize in advance if this seems remedial, but I can’t figure this out.

I built my site in Joomla and just built a new WordPress site for it in a new folder on my server.

The live Joomla site is https://www.theresident.net

I was building the wordpress site in a folder there, https://www.theresident.net/www.new.theresident.net

I’ve got the site to where I want it, so I moved all the wordpress files in the /www.new.theresident folder to the root and changed the address on the General settings to https://www.theresident.net

I get this error: Fatal error: Call to undefined function get_header() in /homepages/24/d281236462/htdocs/theresident.net/index.php on line 1

I am hoping to link out to the Joomla message board from the new wordpress site, so I’d like to keep the Joomla files in place too.

I guess just swapping out the index.php was not sufficient!

I’ve replaced the original joomla index.php so that the site is still up for now.

Any help would be GREATLY appreciated! Thanks in advance.