You are asking about sterility problem but you'll also need to provide data about your last menstruation, cycle duration, period regularity, etc. A sterility problem can be caused principally by the woman, your partner or both people. First, your partner should be examined because medical investigations for male sterility are simpler than for female sterility. A spermogram and sperm functional tests can be performed. Further medical investigations (chromosomal, biopsy) can be done if the previously mentioned exams require them.
For females, the diagnostic procedures are more complicated and include several procedures which could be very unpleasant for a woman (some of them):
1. Hormonal blood analyses (FSH, LH, prolactin, estrogen, progesterone, testosterone, DHEA, thyroxin…) are requested to reveal the function of the axis hypothalamus-pituitary gland-ovaries;
2. Vaginal examination with microbiological smears for STD and PAP-test are standard diagnostic procedures for detecting some possible causes for sterility;
3. Vaginal ultrasounds reveal the anatomy of the inner reproductive organs and some of its functions (endometrial thickness and ovulation);
4. Hystero-salpingo-graphy (HSG)-contrast X-ray procedure will diagnose the conductivity of the uterine cave and tubes;
5. Laparoscopy with hysteroscopy reveal the anatomy of the inner reproductive organs, and
6. Chromosomal or genetic investigations.
First 3 procedures are standard and the last 3 can be done if necessary. You can consult a gynecologist in order to follow up.