Is she amenorrhea from menopause?  What was her pre-insertion FSH level?  If it was >24 then she is menopausal and you would work her up as post-menopausal bleeding with a sonogram and endometrial biopsy.

 

If she is not menopausal, you should evaluate for thyroid disease (TSH, T3, T4) and also rule out an elevated Prolactin level.