They don't have to go back to the IRA but they are definitely taxable if they don't. The money replaces money that was not taxed before it disappeared. If you hadn't lost the funds they would have been taxable so the replacement is taxable as well - but only when you take it out of an IRA.
@YM Kansas
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"