Hello Friend, Good that you are seeking a help. You need to analyze your food, daily routines, time spent non study activities, friends circle etc to figure out a reason. Some of them may be disturbing you both physically or mentally and causing you lack of interest, lethargic, tiredness etc.
No worries. You need to be ready to follow some lifestyle routines, time management, dietary etc to overcome this, if you want to return to normal. Take some counselling support and you will find solutions suitable for you.
Next Steps
Take a counseling support. Feel free to reach out to me online for further evaluation and recommendation.