Now I Am 50, After Married Now 4 Year Running

Now I am 50, after married now 4 year running till date no child, I have now any knowledge sex, and ovulation, some of local doctor tall me you have no sperm, but some doctor says you have between that I and my wife trying, my wife ask my what medicine should not be used but both are O knowledge. please help me through your advise my family more joy and happy life