You could search google for password removers.

http://www.lostpassword.com/

is one. (I've never used it.)

IT Service Agent wrote:

I work at a service desk and I have a user that has forgotten their security
password to open an excel file. I know you can run macros to reset the
password for a workbook or worksheet but can you do the same for a password
required to open the file?

--

Dave Peterson