Hey there! If you perform a new installation of WordPress through the WordPress Toolkit software, it will detect if there are any files present in the existing directory before it performs that work, and give you this error:
Code:
This directory cannot be used because it would cause a conflict with another application installed at /home/username/public_html/test, making this application unavailable.
In my test directory, this was just a blank index.php file. Once I removed that file I was able to complete the installation.
If you had any txt or .html files, it's possible those are no longer being read by the webserver because it is seeing the index.php file created for WordPress. It may be easiest to just rename the index.php file to index.php.bak so it can no longer read that file, and then it would load the original site. You could also use the WordPress Toolkit interface to remove the installation of WordPress on the site.
Can you try that and let me know if that gets things working?