I don't see any sort of "repair" option in the FF14 launcher. I'm dubious such an option would fix GeForce Experience's inability to optimize it though. We may be able to help more if we knew what precisely happened when you tried to optimize with it. In the interim, though, you could always just try the presets available in game to find what looks and performs well for your hardware.

Also, reinstalling GeForce Experience seems more likely to fix GeForce Experience than doing anything with FF14.