In Harry Potter and the Sorcerer's Stone, several ghosts are shown e.g Nearly Headless Nick, Moaning Myrtlee etc, but later it is revealed to Harry that dead can not be brought back to life. Then how come these ghosts exist? Why didn't James and Lily became ghosts as well? Kindly help.
From Harry Potter Wiki:
I wouldn't expect Harry's parents to fall into the "fearing death" category.