The question at the heart of this assignment is a good one, and the instinct behind it is half right. Yes, if you only had the final binary output, reversing the sort would be impossible. But that is not the task. The task is to reverse the *process*, not the sort. The encoding steps were, in order: convert letters to ASCII, sort descending, then convert to binary. To decode, you simply work backward from the end. You take the binary, convert it back to ASCII numbers, and then, and this is the key, you do not try to unsort them. You re-sort them. The original order was lost, but the values themselves are still there. You just need to sort those ASCII codes in ascending order to restore the original message.
This is a common point of confusion, and it is worth naming it clearly: a descending sort is not a destructive transformation like a hash or an encryption key. It is an ordering operation. When you sort descending, you are not deleting information; you are rearranging it. The information about the original order is gone, yes, but the information contained in the values is intact. So the solution is not to reverse the sort, it is to apply the inverse operation to each step. Binary to decimal, then decimal to ASCII, then sort ascending. The final step is not a reversal of the sorting step in a literal sense; it is a reapplication of the sorting logic in the opposite direction.
What does this mean for you practically? It means the assignment is not only possible, it is straightforward if you break it into stages. In Excel, you can use `BIN2DEC` to convert binary back to decimal, then `CHAR` to turn the ASCII codes into letters, and finally a simple sort on the column of characters. The trap is in thinking of the sort as a code that must be undone, when it is really just a step in a pipeline. You are not trying to recover the original order from the sorted order; you are reconstructing the original order by sorting the decoded values correctly.
So here is the concrete takeaway: do not let the word "reverse" fool you. You are not reversing the sort; you are reordering the decoded data. The assignment is testing whether you understand that sorting is not encoding. It is a rearrangement. And once you see that, the whole problem collapses into a few formula columns and a sort button. The user who asked this is not stuck because the problem is impossible. They are stuck because they are thinking of the sort as a lock, when it is just a shuffle. Unlock the shuffle, and the message appears.