How to overcome study depression? I’m failing, and as a result losing my interest in study.

Thank you for taking the time to reach out for help and support. My first question for you would be if there's something in particular that has set this off? Where does the depression come from, or when did it start? Is it specific to the studies, or did something else prompt it where it was carried off to your studies? These questions are important as they help you to better understand what you're currently experiencing and where it stems from.
When you're feeling depressed, It is important to understand that forcing yourself to study isn't going to help you to achieve that goal of studying. When we force ourselves at times, we become less interested and it becomes more like a chore versus something that you're doing for a positive outcome. Since I don't know the prompting factors for your depression or the link that it has to studying, I want to provide you with some steps that you can take that will aide in alleviating/lowering depression, but also help you with improving your studying, interest, and ability to concentrate and proceed with test taking.

When you find that your mind is wandering and that you can't concentrate it's important to let out the thoughts onto paper. You would want to write down what is going on in your mind in either a notebook or a journal. What thoughts are you having or experiencing? Writing helps us to declutter the negative thoughts and organize our positive thoughts. The question may arise of why you are feeling depressed and unable to focus on your studies. This gives your mind ease, because you're taking the thoughts outside of your mind and putting them into a different outlet so that you can think more clearly and understand things more effectively. It is similar to the prompt in question I had identified in the beginning of this post. Sometimes when we set a goal it helps us to build more motivation to do the things that we are not necessarily happy or excited about. This helps us to become more involved in the activity to build more excitement and engagement towards it. Set a specific goal. What I mean by a specific goal is, setting a time, place, duration, purpose, and outcome you would like to see through your studies. When we are specific with our goal, the likelihood of following through increases and we feel more benefit from what we are doing. So set a specific time with your studying. It's also important to break up the study into smaller pieces. The overall goal of studying can seem so complex. So in order to build more motivation with it, sometimes we need to break up studying into smaller pieces. So maybe you study for 15 minutes take a break and engage in something that you enjoy for some time, and then you go back to your studying. This will require less willpower and effort, and could be enough to give you the confidence you need to tackle something bigger and improve your interest in studying.

When we think repeatedly that we are going to fail at some thing, we set ourselves up for that failure. We create manifestation with it, and we end up self sabotaging. Maybe we don't study as hard or derive the time that is needed for studying. So telling yourself that you're going to fail is going to set you up to fail. We need to reframe our thinking. Trying to tell yourself that you aren't going to fail, and that you are going to try your best. This is going to give you a much healthier outcome and prevent self sabotage and manifestation of failing. 
It's important to take control and to accept that the fear will not go away by itself. In fact, the fear is more likely to keep growing so you need to take action if you're going to meet or reach your goals.

Actions that you can take could include analyzing your past mistakes to identify things you need to avoid this time, or like I said previously to break down your study into smaller, less stressful steps. Try to keep a positive mental attitude. Instead of falling into the thinking about what people might say if you fail, try focusing on the task in hand and what you could achieve if you pass. What are gonna be the benefits if you pass? What are you going to get out of it? You can visualize to remind yourself of your goal and picture what your life would look like once you follow through with your studying and was able to pass your exams. When we have this fear of studying, it is a very common reaction to the stress that we feel with learning. Because it keeps us from reaching our goals and following through with the steps needed to study and achieve.

It also seems that you are so preoccupied with some type of feared outcome that we spend lots of time worrying over the seemingly potential risk. Whenever the thoughts begin to occur, you want to remind yourself that this is an anxiety disorder. You want to immediately stop entertaining the thought. This can be very hard to complete since these thoughts feel important and frightening. You want to resist by reminding yourself repeatedly that the fear is not real but rather a symptom of something else. You may want to replace the fearful thought with a new competing thought that distracts you. The new thought requires attention and concentration. In this case, you might want to find a style of studying that functions like this for you. You might want to hand write the key points to the class material. Or you may want to walk around the room while memorizing the key points. If you find this doesn't work, you can try counting backwards from 1000 by threes. This is helpful at gaining some measure of control over your thinking. These are all tools that need to be practiced consistently to help you achieve your goals and break the unhealthy cycle that you're currently in.