there are some common causes of such delayed or absent periods.The common ones are stress, anxiety, emotions, thyroid abnormality, hormonal imbalance, pregnancy, pcos, bc pills, etc.
Since you were recently stessed so it may be the cause of your absent or delayed periods.The psychological factors do play a role in menstrual cycle which may be delayed or absent during the time of stress.
The genital infection may also cause such delayed periods and should be ruled out.The pap smear, blood counts will help us in finding that.
The pregnancy may also cause such absent periods though the chances are less if you didn't have intercourse.
The other causes should also be ruled out.
The treatment depends on the underlying cause.
Let me know if you have any doubt.