For some odd reason my add-ons have dissappeared from the aircraft selection menu. I checked the aircraft folders, but it's all still there. Can someone explain to me what's going on?

I have known people that have had this problem...I know of no fix..You can try a restore point before this happened ..May work...

Did you edit the 'fsx.cfg' file? In that file are the paths to aircraft.

I haven't edited anything. I just uninstalled some aircraft that I wasn't using from my Add/Remove Programs list and I opened up FSX to find my aircraft not showing up.