A locked PDF file can contain two different types of protection. Owner protection restricts the editing and printing of the document. User protection requires passwords to open the document for viewing. There are programs available on the Internet that can unlock the PDF, but some work with only one type of protection and not the other. If you are not sure what type of protection the document has, use a PDF unlocker that is capable of removing both.
Download and install PDF Password Unlocker (link in Resources). Launch the program and follow instructions to attempt to unlock your PDF. This PDF unlocker has three different types of password recovery methods: Dictionary, Brute-Force and Brute-Force with Mask. The dictionary attack attempts to break the password using words found in the built-in dictionary. Brute-Force tries all possible letter and number combinations for the greatest chance of recovery. Brute-Force with Mask is best used when you know the length of the password or a few of the symbols.
Download and install PDF Password Remover to decrypt a file with owner password (link in Resources). Launch the program and follow instructions to attempt to unlock your PDF. This program removes the restrictions that prevent editing, printing and other modifying of the original file. It does not remove user passwords that must be entered when opening the file. It supports dragging and dropping of PDF files onto the software. There is a fee for the full version, and the trial version will only process half of the pages in the PDF.
Download and install PDF Password Remover for Windows (link in Resources). Launch the program and follow instructions to attempt to unlock your PDF. This tool removes owner passwords when you right-clicking the PDF and selecting "Decrypt with AnyBizSoft PDF Password Remover" from the menu. It takes a few seconds to remove the restrictions. It uses two decryption modes, batch and single. With batch decryption you can decrypt up to 200 PDFs at once. With single decryption you can right-click a PDF filename in the Explorer window to get a context-menu item to decrypt that file without first launching the software. There is an option to remove user passwords, but only if you type it in first. If it is entered correctly, you will no longer have to type it in.
Upload your PDF into the PDF Password Online Remover (link in Resources). Launch the program and follow instructions to attempt to unlock your PDF. This is an online decrypter that will remove owner restrictions on the uploaded file. If the file has a user password, you must know it and enter it correctly into the text box. The removal process is instant, and can be done two different ways. You can either click "Browse" to locate the PDF on your hard drive or enter a URL where the PDF is located.
Download and install Advanced PDF Password Recovery if you need to remove all restrictions from your document (link in Resources). Launch the program and follow instructions to attempt to unlock your PDF. It supports all versions of Adobe Acrobat and can recover forgotten passwords. A batch mode automatically processes multiple files. The program is compatible with multicore CPUs. The Standard Edition is good for basic recovery, but you will need the Pro or Enterprise Edition if the user password is unknown.
Do not attempt to open a password-protected file that you are not allowed to view. Use these technologies only if you have lost a password to your own PDF file.