You never find out. All we know about her is that she is a ghost who haunts the girl's toilets that she died in. She was crying in the toilets after being teased, when she looked in the eye of Tom...
harry had to speak parceltoungue to a tap which had a snake on it and then all of the walls moved and it made a big tunnel going to the basilisk.
She lives in a lavatory now; she used to be a Ravenclaw.
Myrtle is Moaning Myrtle's first name.
Olive Hornby