I see the scenery, no problem. It last for 5 mins or so. I also see the Addon Manager menu but there are no sub menu`s inside it. There is nothing at all in the addon manager menu.
I'm sorry, but that just not possible. If you don't have any sub-menu, it could happen if you deleted the bglman*.dat files, but that would result in no scenery shown as well. So, if you have the scenery, you should have the sub-menus as well.
UNLESS, but this is a very unlikely case (not impossible, just very unlikely) ANOTHER program in Windows has "stolen" the menu ID, which is a number from 0 to 65536, but is shared across the whole system so, if another application that started before FS9 has registered its own menus and, by chance, has used the same IDs of the Addon Manager, the menu creation failed.
In this case, the only possible solution would be that you try to stop as many started programs as you can before starting FS9 and hopefully, the conflict might be resolved.