As a capacity as a labelled 'master', I was called in to investigate so-called ghost possession of youths many times only to be concluded as 'mental disturbances' due to either school related, and lately; intranet related.
If you recall that people are generally grouped into 'doer' or a 'thinker'.
If a 'doer' experienced cyber bully, he/she will tackle the person head-on and most probably forgotten about it after a while.
However, if a 'thinker' faces cyber bully, he/she would just keep what the bully said in mind for a very long time. A 'thinker' would keep thinking why the bully is so cruel towards him/her over and over again. If further stimulation are added, such as a scold by the teacher or a scorn by a friend, this person will jump over the balcony abruptly.
People who does not understand how our mind works would be surprised with such a tragic ending.
Unless the bully a person suffers from is of life threatening in nature, there is practically nothing anyone can do: the school, the parents or even friends are just too busy to bother about some minute quarrel in the intranet.
So, if you are a 'doer' or even a 'thinker', then the best way is to use Dudjom Rinpoche's method:
There is a very useful technique a person can use too:
A person can imagine that all the negative energy from cyber bully is absorbed into the HUM in his/her heart. Then started to sing out loud: "HUM, HUM, HUM..." until all of the contaminated energy is gone.
I just realized from a local news report that even teachers in schools can be big bullies to the kids too... while mind training method is good, as parents; they too have a role to play over their children's safe growing.
All of a sudden, it is not so easy to be kids these days!