conception is a complex process which needs several phases. First, the ovaries have to be present. Since they work separately, missing one and the other being intact might be enough for conception. Proper sexual production is needed regardless of the number of ovaries. Once the egg is released, it enters into the Fallopian tubes, where it waits for a spermatozoid from the semen. The actual fertilization occurs in the Fallopian tubes. Several days after the fertilization, the egg travels to the uterus where it is implanted. Furthermore, the egg develops into a fetus in the uterus where it stays until the delivery.
As you can see by the above mentioned, the fallopian tubes are needed for fertilization to occur. If both Fallopian tubes are missing, natural fertilization cannot occur.
However, in vitro fertilization might replace the important phase of fertilization that occurs in the Fallopian tubes. The in vitro fertilization method consists of taking an egg from the ovary and fertilizing it with spermatozoid under a microscope. Once the egg is fertilized, it is placed in the uterus for implantation.
You might want to consult with your gynecologist about in vitro and other conception methods that would be safe for you, given the fact that the reason for not having the Fallopian tubes and one ovary was not given in the first place.