Apple is a good example. Keep in mind that Apple was "turned around" by one of the founders. That's an example of re-aligning the company with it's original vision rather than altering the vision. I think the latter is much harder but I've never tried.

Wow, I feel stupid now. Maybe I didn't think of Apple because it was an original founder returning and fixing things?

Don't feel stupid! It doesn't happen very often, really. Certainly the examples are few and far between. Turnarounds can happen, they just usually don't.

Interesting observation. Most startups fail, and most turnaround efforts fail. Makes success something you really want to hang on to when you find it.