Losing everything

So I’m turning 20 this December. I had my life completely sorted out till last year, I knew what I wanted to become. So, I’m a child who belongs to a supportive family and I did my o levels with extremely good grades (all A*s) then my A levels too. That too in sciences. Then I stood for elections in my college and became the head girl. Everything was sorted out. This year I had to give one exam and I would get into medical college abroad and I’d go abroad. Everything was set, but I failed my exam. So, not only I have lost my one year after high school I’ve lost my dream of becoming a doctor too. I feel like a complete failure and I’ve pushed everyone away. Including, the only guy I liked. Also, he didn’t even fight to stay. So basically, in 2024, I lost my dream, my goal, a plan and a very dear friend. Now everyday I wake up thinking where did I go wrong? Is it even worth continuing? I feel like I’m too behind in life now. I never thought of any backup plans. I feel so stuck and I don’t know what to do. My life just shattered in front of my eyes and my heart just broke. The only person I would like to share this with, I’ve also lost contact with him. It’s just me and I feel very lonely. How should I begin again? If anyone has ever faced something like this please share. I need motivation to carry on.