How to edit a password protected pdf on my Windows PC?

You need to enter the correct password if the PDF is protected by a password. 

PDF open password is a setting used to protect the privacy and security of PDF files. When the creator wants to restrict others' access to the PDF file, he/she can set an open password for it. When a PDF file with an open password is opened, the system will ask for the correct password, and only after entering the correct password can the user view the specific contents of the file. This password protection mechanism effectively prevents unauthorized users from accessing sensitive information in the file.

In general, if you forgot the PDF password, it is difficult to directly restore the original password, but you can try the following methods to edit password protected pdf file after recovering the password :

First, carefully recall the relevant information when setting the password, such as whether a specific combination of numbers (e.g., birthdays, anniversaries, etc.), letter sequences (e.g., initials, common words, etc.) were used. Sometimes, by recalling these possible clues, it is possible to retrieve the password.

Professional Software: Some professional PDF editing software may provide password recovery features, but the same can not guarantee that all encryption methods are effective. For example, some passwords of advanced encryption algorithms may be difficult to crack by regular recovery means.

For some simple encryption methods of PDF files, if you still remember some of the password information, such as the length of the password, the type of characters contained (letters, numbers, special characters, etc.), you can try to retrieve the password by means of brute force cracking. However, it takes a lot of time and computing resources, and the possibility of success is lower for complex passwords.