I once forgot a 4 digit pin code I had used hundreds of time. It was scary, I thought I was going insane. I had to have it reset. (What I think happened is that I inverted two of the digits.)
Exactly same thing happened to me few months ago. Similar thing not that long before that with normal password. I was afraid that my memories are starting to fail me (we have a Alzheimer disease in our family, but I'm still way too young for that). And when I was teen, I kept encrypted text files with passwords, for which I managed to forget password too. I was lucky that I still remembered most of the passwords inside and was able to reset the rest.
