Why dont you try googling; there is a lot of freeware to crack passwords.
Try this Add-In
http://www.straxx.com/excel/password.html
Just to remind you on the DISCLAIMER (from mcgimpsey.com): Please note that
breaking password protection MAY violate laws or regulations in your
jurisdiction. In the United States (currently) it is certainly OK to break
password protection on sheets that you developed for your personal use, or
for which you have permission from the author or owner. It's probably OK if
you own the workbook, even if it was written by someone else. But neither
Norman nor I are intellectual property lawyers in ANY jurisdiction, so, if in
doubt, ask the original author, and if you can't ask - don't use it!