How did you make it without a password? This isn't supposed to be possible, but maybe there's a trick, and we can work from that.
Not sure. I just went to Security and Certificate Encrypt. Encrypt entire document. When I went to go into the document, I was still able to edit. I closed out, tried to go back in and then it will not even let me see the document.
I just did a test on another document. I made a copy first. I went to Advanced/Security/Certificate Encrypt. Hit Yes to change the security of the document. Then I hit Next, then Next, then Finish. Then I saved the document. When I save the document, it says SECURED next to the name of the document up top. Then, I closed it. I go to try to reopen it again and it gives me:
You do not have access rights to this encrypted document.
Now I cannot open it or do anything with it.
Is there a solution?
I got the same thing. Certificates are tricky things. This is normal behaviour when it's someone else's certificate, which can be sent to you and you can encrypt the file, but nobody else - not even you - can open the file without the original security credentials. Of course you made the certificate but how will you get this to everyone who wants to open the file? Certificate security is very secure, but has a major learning curve and you have to set up a very controlled system for managing certificates. Generally you pay to create a certificate with a trusted authority.
What you probably want is the much weaker password security. You don't have to set a password to open.
Certificate encryption uses a digital ID (yours, and/or the IDs of your recipients) so you must have pre-selected at least in the second dialog panel or it won't work. Have you previously created a saved profile which chose them automatically?
What version of Acrobat are you using? It sounds like 9.
Not sure if I ever created one. I am using Acrobat 8.3.
Let's start with Certificate Security is not the same as Password Security. If you had encrypted the PDF file using Password Security, then whatever password you used to lock the document you would use to unlock the document. It's pretty straight forward, and in the cryptography world it would be know as symmetrical security in that you use the same key (password) to lock and unlock the file. Think of it as using a key to lock your front door to your house when you leave and the exact same key to unlock the door when you return, that's what symmetrical security is.
Certificate security is a totally different beast. Certificate Security uses asymmetrical encryption meaning there are two different keys involved, a public key and its corresponding private key. When these keys are generated there is a voodoo that goes on that gives these two keys a symbiotic relationship in that (and this is the basic tenet of asymmetrical encryption) what one key locks only its corresponding other key can unlock. Either key can lock (really encrypt) something and only its corresponding other key can unlock (decrypt) it once it's been locked. Of these two seemingly magical keys one is designated as a private key that only the key owner has access to, and the other is designated as a public key that the whole world has access to. If you lock something with your private key then only its corresponding public key can unlock it, and yes that means that not even the private key can unlock it. You can also lock something using the public key in which case only the corresponding private key can successfully unlock it.
When you encrypt (think of that as "lock") a PDF file using Certificate Security you are encrypting the file using one or more public keys. That is, you encrypt the file for a list of recipients where each recipient has provided you with their public key and they in turn will decrypt the document using their private key. The number of recipients is theoretically limitless, but practically there is a limit in that each recipient you include will cause the file size to grow a little and at some point you'd make the file size too large for the computer to handle, but for the sake of our discussion think unlimited number of recipients. When you encrypted the file you were asked to select a recipient. If you don't also select yourself as a recipient then you end up locking yourself out of the file, and that's exactly what happened in your case. I see from above that you are using version 8, but I believe it was version 9 where we added the warning to make sure to add yourself as a recipient so as to not lock yourself out of the file (I can't remember if it was version 8 or 9, but since you didn't mention that warning I'll assume that we didn't add the warning until 9).
Unless you added yourself at the time you encrypted the file there is no going back to add yourself later because if you can't open the file you can't edit the file. You are locked out forever. You could ask the person that you included as a recipient to see if they can open the file and remove security, but you would have had to make them a document owner when you encrypted the file. If you restricted their editing capabilities then they won't be able to remove security, but at least you could see the contents of the file.
I know this has all been a bit geeky, and I haven't gone into how to procure a public/private key pair, but I don't want to dump too much data on you in one post. If you need more information let me know and I'll be glad to provide it.