Unable to do as much work I could before

Hello doctor l am 17 years old and I am facing the problem from 6-7 month. I don't enjoy doing the things which I used to do before. This problem has been increasing day by day. I only like to sit down and scroll my phone and I feel lethargic and sleepy all the time. I sleep for 9-10 hours daily. I don't do the things that I know is important. My work efficiency has been declining at a high rate. I can't do much work. Earlier I could study even for 11-12 hours daily but now a days I hardly study for 2-3 hours. Whenever I go to sleep I plan for the next day I start talking to myself. Mostly whenever I am not doing anything, I talk to myself. Maybe due to this I have started forgetting the things that happened just now or I have studied just now. This started suddenly when a very unfavorable thing happened . After scoring good marks in 10 I was supposed to prepare for IIT and Go to a coaching but due to lockdown everything was ruined. I was stressed about my future. please help me