I lost my intelligence. Please help me get back on track

Context: I took a gap year after high school (for an entrance exam which was kind of tampered with my already ruined mental health.) Joined a local uni for CSE @2023 where i finished 1 year but in the 2nd year (2024-2025)i had to take a break due my mental health again. I faced a burnout. I currently feel like i lost my knowledge and sharpness and my brain has gone really inactive and dumb. I used to be really smart and the best in my class at school. Ive decided to join back for 2nd year again in the same uni and i want to have an ACADEMIC COMEBACK. Im starting from scratch. Basic math. Basic computing. Start being physically + mentally fit Has anyone experienced similar experiences and got out of this? Please help me with this journey. I dont know anything about computers. Where should i start?

P.S. ill keep you updated on my progress.