You know why you can't get it? because something is blocking you. Some kind of an energy, human being, emotion or pending task is blocking you from getting it. Find what is blocking you and get rid of it as fast as you can.
If you can't think right while studying, if you can't focus and no words can't be embedded into your mind, it means something or someone is bothering you. What is it? is it your girlfriend, your crush or did you hurt someone? what is it? find it and make a solution for it. If you hurt someone and it is really your fault, say sorry. It can be trough text, email, facebook or any medium. Say sorry and you will see that you will feel better, you will feel lighter and you can focus more on what you are doing.
You can't do something important if you don't have a peace of mind. If you are about to let's say attend a business meeting but you know you didn't leave some food for your kids because you are in a hurry then you will not do well in that meeting. It is like your body is in one place and your mind is on another place, you are physically present but mentally absent. So be responsible and do the little task first so it won't bother you in the end. Take time to remove all the things that you know will block you later. Do what is right before you take the flight.
If you are pursuing a goal and your mind is filled with doubts then you will not succeed. If you are listening to critics and believing them that you can't do it then you will surely fail. Filter your mind, remove all the negative thoughts, only treasure the thoughts that will empower you. Learn to separate the healthy and weak thoughts. Weak thoughts will just summoned fears that will stop you from moving while healthy thoughts will give you hope and strength to keep pushing.
Find what is it that is blocking you, it is easy to do it. Just think for a moment and search for things or situations or thoughts that are making you feel bad, stuck and weak and completely get rid of it. If it is a task or responsibility then do it fast, if it is a bad experience from the past, stop thinking about it. Focus your attention to greater things ahead of you. It is hard but it can be done.
Another thing that maybe blocking you from succeeding are your friends or family members. They may also serve as a hindrance but you are not noticing it because you knew they can be trusted. But sometimes the case is they also don't know that they are making you slow, they don't know that they are stopping your progress. Maybe their advice is poisoning your mind, maybe their invitations are confusing your focus. They don't know it and they don't mean it, the key hear is be aware of what is going on. Be conscious in making the right decisions in your life. It is not that you are completely getting rid of your family and friends but you should know how to say NO when needed, you should know what is the right advice to follow.
Another thing that is blocking you... LITTLE PLEASURES. You will say to yourself "ok I will play a video game for just an hour or two, I will take care of my assignments later because I am almost finish", "I will reply to my client later, I will just watch this last episode of the running zombies". What you don't know is you already spend hours doing those things that aren't giving you benefits. You don't know that those little pleasures already make you lost.
Sometimes it is not your inability or lack of skill to do something that is preventing you form being successful. Sometimes there are things that you don't know that are stopping you and making you weak. Look for those things, eliminate it, trash it, burn it and forget it. Just always stay focus, if you can't focus then force yourself to focus because there is no other way around. You have to feel a lot of uncomfortability in order to claim the victory.