Forgot My Own Talk Today

I'm feeling pretty embarrassed right now. I was supposed to give the keynote presentation today in my seminar class and spent hours preparing for it last night. Woke up this morning, rushed through breakfast, and headed straight to campus. As soon as I got there, everything clicked, it was the wrong day! The talk isn't until next week. I felt so stupid walking into class empty-handed, but no one could have known except me. It's been eating at me all day, wondering how I managed to forget something that important.