After tinkering with your X-Plane or accidentally copying something to the wrong place or inadvertently deleting that vital file, you decide to re-install a fresh copy “from scratch”. Once you have made this decision, be aware that while the installer will scan an existing installation for missing /corrupted files and replace them, it will not delete files/folders that have been moved to the wrong place or stuff which has been added.
For the same reason, you don’t want to install a Second copy into the same folder as your existing installation
To get a proper clean install, the new instance of X-Plane needs to be installed into a new folder.
To avoid confusion seasoned X-Plane users tend to prefer to keep the same base folder name. For example “C:\X-plane 12”. So, for a new fresh installation, first rename your existing installation base folder name to something else – for example rename “C:\X-plane 12” to “C:\X-plane 12-OLD”. Then download and re-install the new fresh virginal copy to “C:\X-plane 12”.
TIP:
Since downloads take a while, immediately COPY this installation to another folder like “C:\X-plane 12-VIRGINAL” which you never access. That way, you have a clean untouched copy. At a later stage you can delete the “OLD” folder