Revert to an un-sorted list

I have a table that was unsorted (it’s names with a few check boxes and notes). I liked it that way because it was in the order of when records were added—and the newest ones that needed my attention were at the bottom. A coworker recently sorted this alphabetically, so now I have no way to identify who are the new records. Is there a way to undo sorting? (I don’t have a field with any sort of date, just as an FYI.)