i am 31 never gotten pregnant, unmarried and still having constant periods wot causes the an ovarian cyst to develop

ALL ovaries get cysts. That is how the egg gets released to travel down the fallopian tube. The egg causes an irritation on the ovary, which forms a functional cyst. When the cyst gets big enough, it pops, sending the egg out to be picked up by the fallopian tube. Sometimes, for whatever reason, the cyst doesn't pop. It just gets bigger. When that happens, there are many forms of treatment, ranging from watch and see to hormones to surgery. These options are best discussed with your doctor. Ovarian cysts typically are benign(not cancerous) and not problematic. Most women don't even know that they have them. However, if it is becoming a problem for you, please see your doctor. Your health is important, even it is just for peace of mind.