She had labour complication at the birth of our only child. She never had her period afterwards and were very sexual . She went to our local doc who referred her to a specialist and had a operation done. They put her on the pill afterwards and everything were fine. She had her period for 4 months and after she were done with it her period stopped. Then her lack of sexual interest started and she only gets horny for a +- a week a month
Is there any way I can get my wife back to her normal self

I wouldn't say there is a normal for women in general! She has been through a lot, and her hormones are in control of the situation, as they are for many women. I think I can say that in general, I only had a few days a month when I felt like having sex (now I'm many years past menopause). And you don't say how old she is. It would be good if she were the one here asking, so she could explain exactly what she has had done and what she is feeling. If the pill helped regulate her hormones, she might want to ask about going back on it.