[remram]

This happened to me, I forgot my Android "pattern", the swiped pin-like thing to unlock the phone. I didn't have a password set. I was able to factory-reset it with my Google account password but I lost recent files that hadn't yet been backed up (photos etc).

I just totally blanked. Like you said, the more I thought about it the less I could remember what it was like. It was really scary.