Tomorrow i will have exactly 4 weeks since i had the abortion, and i want to know if its normal to wake up fine and suddenly i feel sad and cry?

Yes: You can experience post partum depression from abortion or miscarriage just like women who deliver full term pregnancies. Some women also regret the abortion and will have depression or anxiety over it even years later. Its best to see a physician or facility that can evaluate you and see if you need talk therapy or an antidepressant.

Yes, can be normal: Although hormonal changes occur post-partum, I would look at your attitude about having had an abortion. Do you feel a sense of loss? A sense of guilt? Any uncertainty about the choice you made? Does this conflict with any of your religious or ethical beliefs? If yes to the later questions, would explore this further with a confidant or loved one. Having an abortion can awaken deep feelings.