Is there any way to fix a corrupted CFX file? I made no changes or opened the file and suddenly it was corrected.

Correction that is a corrupted FSX.CFG file.

I would turf the old one and let FSX rebuild a new one then just redo your custom entires.

A couple of other things to consider. If you use Windows 7 and have not recently added anything, you might simply revert to a prior "set point". Also, if you end up rebuilding your Cfg file, once you get it to place you are satisfied with it, make a backup in case this happens again.

As Jo says - once you're happy with the new fsx.cfg file - create a new folder, called say, 'fsx_cfg_backup', somewhere - and put this 'master' copy of the fsx.cfg in it, as each time FSX has to create a new fsx.cfg ALL of your hard work tweaking the sim will be gone. All you have to do then is to copy the saved cfg back in place.

I was unable to delete the CFG file, reverting to an earler version or using the FSX disk to repair did not help. Finally out of things to try I restarted in the safe mode and the corrupted CFG file was gone, I placed a saved CFG file in the folder, even then FSX would not start. With nothing to loose I reinstalled Service Pack 1 and on the next attempt it started with the message that the last flight was corrupted and would start with the initial screen you get showing the Tryke. I then selected another saved flight, redid the CFG file and it has been working OK. Go figure!!