Hey, welcome to the forums first of all
As for that, yeah they would have been protected and so are not accessible anymore
Had this alot recently.
Next time if you want to lock documents, try and use a zip folder, and put a password on it. This seems a better option
As for that, yes, on your new account, just use the backup disk to place the pictures and videos back on.
Don't lock this time hehe, though you didn't know you even had!
You could also place it on an external disk yeah,
though if this is just your protected My documents folder copied across, I don't know, adn probably isn't
I'm sure somewhere though, someone has created a program to hack into these, though I wouldn't know where to start, and would be counted as illegal though it could have some useful features.
Hopefully you just saved the files within it so it will be possible
Hope this helps