How do I recover data that somebody pasted over on the wrong page

From: Randy <Randy_at_discussions.microsoft.com>
Date: Sat, 1 Jul 2006 09:46:01 -0700

An employee copy and pasted to the wrong page into a worksheet that had very important information on it and lost all the data that was there and then saved it. Is there someplace to recover the data to the time before he saved it incorrectly? Received on Sat Jul 01 2006 - 09:46:01 PDT