There are a number of options available, depending on the main issue you are experiencing.

Weight loss can be more difficult because of the higher levels of testosterone, but it has a very beneficial effect on balancing hormones and restoring regular periods in obese women. So exercise and a change of diet could have a significant impact.
Insulin sensitisers, such as Metformin, reduce the impact of insulin resistance and can also assist in weight loss.
Ovulation inducing drugs such as Clomiphene (Serophene or Clomid) can stimulate the ovaries.
If you do not respond to Clomiphene, injectable drugs (FSH) can be used, but these require specialist facilities and close monitoring of the response to avoid severe side effects and multiple pregnancies.
IVF treatment may be necessary in very difficult situations.