In the board menu, there should be an option to view archived cards/lists.
On desktop/browser, click More and then there should be an Archived Items menu option:
On mobile (at least on Android, not sure if iPhone is the same), there should be a menu option for "Archived Items" when you open the menu, as well.
Once you have the card open, there should be the option to "Send to Board" instead of the "Archive" button.
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