I have a long spreadsheet list of employees and their scores/strength in various tasks. I use the Sort function (under Data) to re-arrange the list in many different ways, but I have found that not all of the data is sorting properly. Many numbers are clearly in the wrong box. The list has been re-arranged in dozens of different ways now, over the course of weeks. It's not something I can just Cmd-Z and undo.

How can I can undo this damage, and how do I get the Sort function to work properly? There are 500+ employees. I really, really, don't want to have to go back and have all the information re-entered again.

I'm using Excel 2008 for Mac, if that's important. When doing a sort, it allows you to enter up to three criteria. I've sorted by 1, 2, or 3 criteria in many different ways.