I am trying to make a new start and studying, but forgetting things is a problem for me
The questioner's philosophy
Problems with memory can stem from many factors. The #1 likely suspect is stress. If you are feeling overwhelmed with academic pressures, dealing with the loss of your parents, or other significant stressors then your memory will be severely affected. I would recommend you talk to a counselor or therapist about the loss of your parents. How has that impacted on you? Is life really scary now that you've lost these two principal people in your life?
I suspect your memory problems are a symptom of something deeper that's bothering you. And I suspect that it has to do with losing your parents. When we are overcome by grief, especially at an unconscious level, all our normal functions are affected. Talk to a counselor first and see if you need to address your losses in a more formal way - with a Grief Support Group as an example.
Are you also having problems making simple decisions? Are you worried about another tragedy impacting your life? Are you feeling frightened about life now that you've lost the support of your parents?
It is simply not possible that you can easily set aside the loss of your parents and continue with life as if nothing has happened. You have had a major shock. You are probably still in shock. And because of this shock, and incompleted grieving process, your memory is not functioning. The book I have authored called "How to Cope with Grief and Loss" will certainly aid your recovery process.
Academic pressure is another source of stress, of course. And this too can have an impact on your memory function. If you do not know how to go about studying properly, it is very easy to get in a mess and behind with your studies. If you get behind, it is hard to catch up as the new things you are taught are incomprehensible without a good understanding of the earlier foundation, that may be like shifting sands for you. A stressful situation and one that only good study skills can remedy.