My missions have been deleted

I'm truly sorry to hear that you've encountered this issue. I can understand how frustrating it can be to see your other missions disappear after the installation of an addon. But fear not, let's try to tackle this step by step.

Firstly, it's crucial to understand that the missions in flight simulators like Microsoft Flight Simulator X, and indeed the 2020 version, and X-Plane 12, are stored in specific directories within the game files. When you install an addon mission, it should ideally populate within these existing directories and not overwrite them.

Before we proceed, let's start with a terminology refresh:

Directory: In the context of computing, a directory is a file system cataloging structure which contains references to other computer files. Think of it as a 'folder' within your computer's file system.

Now, here's my hypothesis on the problem you are facing: It seems like the addon mission you installed may have been packaged incorrectly, causing it to overwrite the entire missions directory rather than adding itself to it. This would explain why you can only see the addon mission in your mission list in the game.

Steps to rectify:

Locate the Missions Directory: The first thing you need to do is find the Missions directory in your game files. For Microsoft Flight Simulator X, this is typically located in the following path: C:\Program Files (x86)\Microsoft Games\Microsoft Flight Simulator X\Missions.

Inspect the Files: Once in the Missions directory, inspect the files to ensure all the mission files are still there. If they're present but not showing in the game, the problem could be a faulty missions.cfg file.

Recover/Repair Missions.cfg: The missions.cfg file is what the simulator uses to populate the missions list. If this file has been corrupted or overwritten by the addon, it could be why you're only seeing the one mission. If you have a backup of this file, restore it. If not, you might need to repair your game files (a step we'll discuss below).

If these steps don't work, I'd recommend trying the following:

Uninstall the Addon: If the addon mission is the root of the issue, uninstalling it might restore your previous missions. However, I understand from your question that this specific addon isn't listed in your files. If that's the case, we'll have to resort to a complete reinstall.

Complete Reinstall: Uninstalling and reinstalling the simulator should refresh all the game files, but from your message, it seems you've already attempted this without success.

Repair Game Files: If the complete reinstall isn't working, there might be some residual files that aren't being removed during the uninstallation. You can attempt to repair your game files instead. Steam users can do this by right-clicking the game in their library, going to 'Properties', then 'Local Files', and finally clicking on 'Verify Integrity of Game Files'. This should find and fix any issues with your game files.

Remember that these steps should also apply to the latest versions of flight simulators (Microsoft Flight Simulator 2020 and X-Plane 12) should any of you encounter similar issues.

Lastly, moving forward, to prevent such instances, I would recommend installing addons one at a time and checking to ensure they're working correctly before installing the next. This will help you identify any problematic addons more easily.

I hope this guide proves helpful in resolving your issue. If you continue to experience problems, feel free to reach out for further assistance.

Safe flights!