How can you tell if only one of your ovarys is working? and should i be concern?

Do not worry: Monitoring for ovulation with transvaginal ultrasound will confirm if both ovaries are working, but you'd have to do it for several months, maybe up to a year to be absolutely certain. At 20 years old (is this correct?) it would be r-e-a-l-l-y unusual for one ovary to not work unless you've had some sort of surgical problem with that ovary. Why do you think only one ovary works?