It seems your scenery.cfg has been destroyed
You can try one the following:
- Go into the %ALLUSERSPROFILE%\Microsoft\FSX folder, and look for files. The scenery.cfg should be there. Try to open it with Notepad and see if there's something clearly wrong. Or, check this folder to see if the installer created a backup of it as it was before, or if another previous installer created a fairly recent safety copy.
- If this fails, and you can't recover any valid scenery.cfg, there's a backup in the main FSX folder BUT, this is a "clean" scenery.cfg, that contains only the default sceneries, as if FSX was just been installed so, if you copy this file (or remove the one in the %ALLUSERSPROFILE%\Microsoft\FSX folder), you'll have to reinstall all your sceneries. Not FSX, but all the addon sceneries.