Unprotect a Word Document

One possible solution. I think there are others as well.

1. Open a protected document in MS Word
2. Save as "Web Page (*.htm; *.html)", close Word
3. Open html-document in any Text-Editor
4. Search <w:UnprotectPassword> tag, the line reads something like that: <w:UnprotectPassword>ABCDEF01</w:UnprotectPassword> (password is already in hex-format)
5. Keep the "password" in mind
6. Open original document (.doc) with any hex-editor
7. Search for hex-values of the password, which is stored in reverse order. (e.g. If password is 0xAB 0xCD 0xEF 0x01. Then the password is in the .doc file as 0x01 0xEF 0xCD 0xAB)
8. Overwrite all 4 double-bytes with 0x00, Save, Close
9. Open document with MS Word, Select "Tools / Unprotect Document" (password is blank)

If you mean the one required to open the document, it depends on which version of Word was used to create it. There are several "Word password remover" programs on the internet, but Word 2003 and later use a much stronger encryption algorithm for which those will not work.