My girl has not menstruated for close to 8 months now and she is not pregnant. what could be the course and what is the solution?

2ary amenorrhea.: Secondary amenorrhea should be investigated by a gynecologist and/or a reproductive endocrinology specialist. It could be caused by a variety of reasons, such as obesity, ovarian tumor, chronic anovulation/hyperandrogenemia, thyroid dysfunction, stress, anorexia nervosa, excessive training or marathon running, oral hormone therapy, uterine scarring from prior instrumentation or infections etc.