For both of these tips you'll need to be in the X-Plane root folder:
- Start STEAM. Goto LIBRARY.
- Right click on X-Plane
- Choose Properties.
- In the rising window choose LOCAL FILES.
- And than choose BROWSE LOCAL FILES.
- Now you are in the X-Plane Main (Root) Folder and you see the path in your file explorer.
Move the preferences folder (found in the Output folder) to the desktop, then restart X‑Plane and default preferences will be restored. If the default preferences do not fix your problem, you can simply replace them with the folder you moved to the desktop and restore your personalized settings.
The final common culprit is third party add ons, such as scenery and plugins. Try moving the Custom Scenery folder and plugins folder (found in the Resources folder) to the desktop, then restart X-Plane.