Go to your Recycle Bin.
Find you folder titled "aircraft".
Right click on "aircraft"
Select the option "Restore" (It will take some time to finish)
If you have a large Aircraft folder, there is a chance that the Restore may fail. This happens sometimes when restoring LARGE files.
There is also a chance that some files might not work correctly, this happened to me when I "Restored" my Gauges folder.