Hi,
    I understand your concern.
    The causes for the delayed period after tubectomy are variable-
    * - Weakness following illness/ Psychological 
stress, may cause late menses , It can be treated by giving a short course of hormones -followed by menses.
    In case the menses do not start/ same problem continues in following month also-You need investigations for-
     - severe 
anemia, thyroid problem, problem of uterus( 
fibroid) ovaries (PCOD,
cyst)are other common causes which need to be excluded.
     - you will need pathological tests like CBC,
Thyroid function tests,blood sugar&USG pelvis to pin point the cause.
 *   Please consult your gynecologist after physical examination & investigations,the diagnosis will be clear ,& you will be advised specific treatment there after.
  thanks.