I was very sad to hear that you were suffering in your studies. I would like to share some advice with you on how to study efficiently.
Firstly, you can talk with some close friends about your problems and ask for their help. This is an important way to deal with your problems directly. Secondly, try to study in a positive way. This will decrease your study pressure, making studying an easy job. Third, spend time doing exercise. Not only dose exercise build up our body, but also it provides time for us to refresh our mind. Last, you can listen to some soothing music, which will be a good way to improve your current depressed mood.
I hope all this information can benefit you.