Describe a time when you forgot/missed an appointment

One appointment I clearly remember missing was a dental check-up about a year ago. It was scheduled for a Saturday morning, and I had actually booked it two weeks in advance because my tooth had been bothering me a little. The problem was that the week before the appointment was extremely hectic, with work deadlines and a family event, so it completely slipped my mind. On the day itself, I woke up late, had breakfast slowly, and started doing some housework. Then, around noon, I checked my phone and saw a missed call from the dental clinic. At that moment, it suddenly dawned on me that my appointment had been at 9 a.m. I felt really embarrassed because I knew the clinic was usually fully booked, and my absence might have wasted someone else's slot. I called them back immediately, apologized, and explained that I had mixed up my schedule. Luckily, the receptionist was quite understanding, although she reminded me to cancel in advance next time. I had to wait another week for a new appointment, which was inconvenient because the toothache got slightly worse. Since then, I’ve become much more careful with appointments. I now put everything into my phone calendar and set two reminders, one the day before and another an hour before. It was a small mistake, but it taught me to be more organized and respectful of other people’s time.