Ideas:
1. ask the person who created the file for the password.
2. ask the folks at
www.adobe.com (they have a forum)
3. search Google for "password cracker adobe pdf"
The intention of passwords on PDF files is to protect against just
exactly what you are trying to do. I'm sure there are ways around this
security (or at least have heard there are, but it is not in compliance
with what the originator intended. That's why you should contact them.
Hope this is useful to you. Let us know.
rms