Rewind

• WWizards of the Coast2020-06-23
  Official Ruling
  Rewind targets only a spell. It doesn't target any lands. The lands are chosen as Rewind resolves.
• WWizards of the Coast2020-06-23
  Official Ruling
  If the spell is an illegal target when Rewind tries to resolve, perhaps because it was countered by another spell or ability, Rewind won't resolve and none of its effects will happen. You won't untap any lands.
• WWizards of the Coast2020-06-23
  Official Ruling
  You can choose up to four lands, no matter who controls any of them. Those lands untap once. You can't choose one land and have it untap four times, for example.

Rulings via Scryfall