There is no such medicine or cream which can lighten your complexion.
It is hereditary. All these creams n medicines are only methods of money making. Be content with whatever is your complexion. Don't underestimate yourself in terms of skin color, see yourself from the eyes of your mother, you will find yourself to be the most beautiful person.
It’s the internal beauty that matters.
I know it is difficult for you to agree with me. U are too young. Pay full attention to your studies and achieve something in your life. U will see then complexion doesn't matter. Perhaps then you will understand the meaning of what I am trying to make you understand you can do the following to get glowing skin
you can apply aloe vera
juice/gel from its leaf (fresh), not from ready made gels available in market. Remove skin of an aloe vera leaf. Take /scoop out gel. Apply this gel to your skin. Wash with plain water after an hour. Or keep it overnight.
Use some sunblock with spf (at least 50) every time you go out in sun. Apply it 30 mins before going out
use umbrella when going in sun.Drink plenty of fluids.Don’t be stressed.