After installing T360 all my aircraft and other add-ons disappeared so I uninstalled T360. The result was the sim worked but all add-ons didn't.
It seems that product installer has corrupted your FSX.CFG, most likely it might have mistakenly removed one of the default SimobjectPaths, so any other addon that requires that folder to be present (GSX and all our sceneries), will stop working.
Open your FSX.CFG at %APPDATA%\Microsoft\FSX, and look all the lines containing this:
SimObjectsPaths=
Be sure there's a path listed for the Simobject\Misc folder, and all the numbers are in sequence