What is the role of the afterlife in Harry Potter and the Chamber of Secrets? Consider Nearly-Headless Nick and Moaning Myrtle as examples of characters who continue to affect the plot even after they are dead. Why do you think Harry's parents are not able to return to earth in this ghostly form?
Although a motivating force in Harry Potter and the Sorcerer's Stone is the avoidance of death, death is not seen necessarily as an end. Voldemort, who has been almost dead for quite some time, has figured out ways to affect the world dramatically. The fact that he goes to great lengths to stay alive implies that once he dies, his power to affect the world will be obsolete. Yet Myrtle and Nick both have their roles in life at Hogwarts, and although neither are particularly happy, they are moving, active figures who interact with and affect the lives of students. Nick is alive enough that he is even able to be petrified by the basilisk.
A paradox of the novel is that these two ghosts remain, but Harry is unable to see his parents. The ghosts haunting Hogwarts are there because they feel it is the best place for them to be. Myrtle is most satisfied when given the chance to mope and complain (recall her delight at being about to talk about her death), and alone in her toilet is a fitting location for his. Nick is still in the Hogwarts castle, interacting with students and keeping them out of trouble, and perhaps he is there because he cannot fit quite so well anywhere else. He is not headless, and therefore cannot be off somewhere participating in the Headless Hunt, so he remains where he is happiest for the time being.
Harry's show themselves to Harry in the first book, through the Mirror of Erised, and then again in the fourth, when they appear as prior spells from Voldemort's wand. In each case, they appear to help him understand something, and to offer him protection from danger. If they feel that their best state is one in which they can help Harry, then they would not return to be near him, but rather leave him marked with their love and memory and then let him go his own way. Harry's greatest acts of wizardry counter Voldemort's power, and part of Harry's desperation is that Voldemort has killed his parents. If Harry's ultimate purpose in this series is to defeat Voldemort entirely, then it is necessary that his parents cause Harry to feel their absence, to feed his need to avenge their deaths. In this way, his parents are handling their afterlife in the best way possible, even if it means that Harry is unable to see them.
How do Harry's and Lockhart's attitudes toward fame act as foils to each other?
Harry grows up with fame, understanding that his past has left him with an obligation to live up to his heritage, while Lockhart views fame as the ultimate end, and cheats, lies, fakes, and smiles his way into fame. Lockhart spends the entirety of the story giving Harry pointers on how to handle fame, but Harry is entirely uninterested. It is no surprise that Lockhart is a fraud; he does exactly what the novel seems to warn against. He allows himself to become arrogant and lists all of his awards and honors under his signatures, boasting that he could take on the Chamber monster. Each episode of the novel, however, reveals him to be progressively more incompetent. Harry, on the other hand, never leans back on his fame as a means for special treatment or privileges. He views the marks of his past as tools he must use to the best of his ability for as long as he can, whereas Lockhart seems to believe that once he has a few books and awards under his belt, his fame is secured.