In the book Speak, main character Melinda Sordino has been the victim of a rape. Throughout the novel, she is attempting to deal with the social and emotional outcome of the rape and, of course, is having a very difficult time. One symbol that is particularly present throughout the course of the book is that of mirrors.  

After the assault, Melinda begins to hate mirrors. Every time she sees a mirror, she feels disgust for herself, for the image that she has become. She has taken to nervously chewing on her lips and picking at them, and this causes her to shy away from her own reflection, sinking even deeper into self-loathing. At one point, she goes shopping alone, relieved to be by herself.  Yet, when she goes into the dressing room, she feels horrified at her own image in the 3-way mirrors; She has gained weight, and she says she can see “reflections of reflections, miles and miles of me." She adjusts the mirror so that she looks like a Picasso painting (chapter 14). 

Finally, she gets her revenge on both her rapist and the mirrors which she so despises.  In chapter 89, towards the very end of the book, she is followed to her secret closet in the school by Andy Evans, the boy who raped her at the party. He threatens her, accusing her of lying and telling her that he will "give her what she wants" (chapter 89). Instead of retreating into herself, she decides to take action, throwing something at the poster of Maya Angelou, one of her heroes, and breaking the mirror behind it. This momentarily startles Andy away from his attack. Grabbing a piece of glass, she holds it up to Andy's neck. Finally, he is the one who can't speak—not her. 

In Speak by Laurie Halse Anderson, what does Melinda do to the mirror?

After she undergoes a traumatic rape during her first high school party, Melinda does not report the incident to anyone. However, her silence only causes her distress and mental turmoil. Her situation is worsened by the isolation she experiences from her busy parents and judgmental friends.

She hates herself for what happened and cannot stand to look at her reflection because she thinks she is ugly. Therefore, Melinda avoids mirrors at all cost. At home, she hides her mirror at the back of her bedroom closet. In the broom closet where Melinda seeks refuge while at school, she covers the mirror with a Maya Angelou poster the librarian had given her. The only mirror she seems to have tolerated is the three-way mirror at Effert’s, which she equally manipulates to distort her reflection in order to resemble one of Picasso’s sketches.

Mirrors are a constant symbol in Speak. Melinda hates mirrors because they remind her of what she perceives to be her ugliness. She hates them so much that she actually covers them up. She literally cannot look herself in the eye. Mirrors reflect the way that the world sees Melissa, a highly negative image she increasingly internalizes.

Towards the end of the story, however, the mirror comes to take on a completely different significance. Andy tries once again to rape Melinda. It was his violation of her the previous summer that precipitated the immense psychological turmoil that she's been suffering ever since. But this time she resists. Melinda's always hated herself for what she perceives to have been her weakness in not preventing Andy from raping her. Now, however, she smashes her closet mirror and uses a shard of broken glass to threaten Andy.

This time, Andy backs off. For Melinda mirrors are no longer a symbol of poor body image and lack of self-esteem; they represent a sense of empowerment and control, a means of fighting back against a cruel world and establishing herself as someone to be valued and respected: someone that was there in the mirror all along.