How to unlock/unprotect excel sheet without password

Unlock by modify xlsx file:
1. Rename the file extension from xlsx to zip.
2. Go into the xl\worksheets folder.

3.  Right click on the worksheet you want to unprotect and select edit.
4. Look for the sheetProtection tag and delete:
<sheetProtection password="96E1" sheet="1" objects="1" scenarios="1"/>
If you choose to set an empty password, the worksheet is still protected but you can unprotect it in Excel without entering any password.
5. Rename the file extension from zip back to xlsx.



http://datapigtechnologies.com/blog/index.php/hack-into-a-protected-excel-2007-sheet/
http://uknowit.uwgb.edu/page.php?id=28850
http://deinfotech.blogspot.com/2011/08/unprotect-password-protected-excel-2007.html
http://windows-passwordrecovery.blogspot.com/2012/11/how-to-crack-excel-password-without-any.html