Have you tried reloading a save from before it happened?

Try transforming into a werewolf or Vampire Lord

If you haven't restarted your console yet do that, if that doesn't work, load a save. If that doesn't work, fast travel. Of that doesn't work, use things that alter your characters appearance (dragon aspect shout, transforming into werewolf or vampire lord, using potions if the phantom, etc)

If that doesn't work... You're probably sol

If you play pc, exit the game to your desktop and that will work. The same thing happened to me where Solsthiem looked like Apocrypha where everything was green.