According to Microsoft® Policy Regarding Missing or Invalid Passwords:
Microsoft engineers cannot help you break the passwords that are applied to the files.
If you need help to break or to reset a password, you can locate and contact a third-party company for this help.
Here it is:
Advanced Office Password Recovery (AOPR) is ElcomSoft's comprehensive recovery suite supporting all versions of Microsoft® Office including Office 2010.
AOPR (a favourite of the FBI et al) is available in three editions: Home, Standard, and Professional. The key features of each AOPR edition are documented at Supported File Types and Passwords.
Get more information about Advanced Office Password Recovery
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