This free software is designed to recover Excel file open passwords. Although Excel includes several different password types including workbook, worksheet and range passwords, file open passwords are the most common password type used in protected Excel documents. It is often easy to forget the password, or for someone to protect a file, then leave an organisation, and this software can help you open the file.
Free Word / Excel Password Recovery software is particularly effective when a common Excel password, or if a fairly short password was used (long passwords can be infeasible to recover with this sort of software due to the time required). It works by trying passwords against the file until one matches.
The file open password is combined with an internal counter to generate an encryption key that securely encrypts the contents of the Excel file. The XP and 2003 versions include a choice of extremely secure encryption approaches that the file owner can choose from.
This software won't recover VBA macro passwords, workbook or worksheet protection passwords, but again other packages are available to do this, or you can use a Passware Kit Basic.
You can try this software which is fully featured and completely free before outlaying money on a recommended commercial package, such as Ultimate Zip Cracker (see the side menu to download this package), or using a commercial recovery service. It includes more functionality than many costly commercial packages, but since it is free you are not risking anything by trying it.
If you run Windows Update regularly on your system, you should already have everything you need, otherwise you can download the prerequisites and the software from the Download page.