Hi Blaire,
If I understand you correctly, then the original workbook
is still intact under it's old name. Since when you use Save As
you create a new workbook. Unless you never saved the
file before. Excel is a spreadsheet application, but the word
spreadsheet is rather ambiguous in Excel, as to whether
one would be referring to a workbook or a worksheet.
If that was a save as and you ok'd the replace - too late I'm afraid
Steve