I did use the "easy apps" installation from my webhost (I guess that is "Fantastico") ... and unfortunately, I have done alot of work on the site. I thought I had done everything properly but obviously I was mistaken.
I did find the article 122 but wasn't sure if it applied as the first thing on the list was to determine the "new foldername where your zencart files will be running from" and I thought it needed to run from the root directory not from a folder.
So, can I follow the instruction in this article to solve my problem and do a fresh (manual) install?
https://www.zen-cart.com/tutorials/index.php?article=100
I have already created a backup of my site (FTP - copied all files, and used phpAdmin to backup the database). All files are stored on my computer.