What does User password mean for your PDF?
This is the one banks and insurers use when they email a statement: the file opens only after you type your date of birth or the last digits of an account number.
It is real protection, because the document’s contents are encrypted with a key derived from it. Nothing can display the pages without it, and nothing here guesses it.
If you know it and are tired of typing it, a decrypted copy opens like an ordinary PDF and keeps every page, link and bookmark.
What happens if you lose a user password?
The document is gone. There is no recovery, no reset and no master key: the password is what the decryption key is derived from, so without it the pages are ciphertext and nothing — including the software that made the file — can display them.
Sites that offer to recover one are describing a guessing attack. It works on weak passwords and fails on everything else, and it means handing your encrypted document to a stranger for the attempt.
If a bank or insurer set the password, the answer is almost always in the covering email: a date of birth as DDMMYYYY, the last digits of an account or policy number, or a postcode with no space. Those formats are chosen to be derivable rather than secret, which is also why they should not be mistaken for real protection.