Sometimes, it is essential to reset your content.xml file (e.g., when you miss procedures, waypoints, legs missing from the nav devices, third-party scenery issues, etc.). This file will automatically be recreated at the next start of the sim.
You will find the content.xml file here (attention, the location is changed since SU3 - it´s now in a sub-folder, with your xbox-game-tag-id):
Sim from Marketplace:
%localAppData%\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\<your game tag id>
Sim from Steam:
%appData%\Microsoft Flight Simulator\<your game tag id>
PLEASE! Don´t re-order or re-name the navdata packages - this is not necessary any longer since SU3 and can result in an undefined state of the sim
Cheers,
Richard