We marriage 4 years ago and my wife can not be prgnant ,and we have the same blood group which AB+ , so my question is why she can not be prgnant ? I need your help

Have you and her been to a doctor and been checked, she may not be getting pregnant because of the husband, it is not always wife issue.

So have a doctor check out all the medical possibilities. Next what methods to get pregnant, is the most fertile time of month tracked and sex done only during most prime times.

Having the same blood type isn't an issue. Many people with the same blood type have babies every day.

The issue would either be with your sperm or her ovaries. After 4 years you should seek the help of a fertility specialist.