First of all, breathe. You missed an appointment. There are greater catastrophes in life! I’m sure a week doesn’t go by that most doctor’s offices have a handful of no-shows.
Second, you or your parents need to call the place and explain what happened. If they regularly deal with depression, I’m sure they’ve seen this before. The worst thing you can do is burry your head. Depression requires some kind of treatment. I’ve never met anyone who got a handle on it on their own. Places that worked with depression know what they’re dealing with, and want to help you. You just need to keep them in the loop.
Third, maybe see if your parents can talk to their insurance provider and see if there’s a depression counselor who can meet you over Zoom.
Finally, talk to your parents (anbd/or friends) about helping you with all the habits people in this thread are suggesting (like setting alarms and reminders). Habits a good in that they bring some structure to your life. That can help.