Recovering data from Ms Excel

I have been facing a problem with opening an excel file. Actually I am using office 2000 on Windows XP. And I have an excel file containing a very important data related to my personal income and expenses for the year. But the file no more opens. Unfortunately, I didn’t save the file anywhere else.
Please help me out in resolving this issue so that I could recover my important data and save it somewhere. Please help me out in this matter.
