Trapped -- part 1

All seemed strange. Though it was my own flat, now... nothing was known to me.

Mithila lived alone in the city for her job. She had friends and relatives but preferred staying all by herself. She never wanted to be a burden on anyone. Her parents were proud of her ambition, her passion, and determination. They supported her in every possible way. 

Mithila was a psychology professor. Also, she was working on a project with her colleagues on human behaviour. She wanted to contribute to the field of psychology as much as she could. She was a part of many associations regarding the subject. 

Once, Mithila's cousin Namrata came home. She was a caring mother. But, her son was undergoing some mental pressure. His name was Aashay. Aashay stopped socialising much. He spoke less these days. This troubled Namrata.

Namrata asked Mithila to talk to Aashay. She could not see her thirteen years old son becoming so rigid and mature. Mithila agreed to this. She was ready to help her nephew, who was as dear to her as her own son would have been. Mithila asked Namrata to leave him alone with her. Namrata followed. 

Aashay sat just opposite Mithila. He did not say a word. He just looked all blank. His face is just emotionless. Mithila initiated. 

She asked, " Dear Aashay, would you like to eat something? Chocolates? Fruits? Or some milk?"

"Nothing!" was his reply to the question.

Mithila tried asking him about his school, his friends, his parents, and other relevant topics a teen has in his life. But all these questions were answered in "Yes", "No", "Do not know" and such phrasal replies. 

Later on, one question just baffled him. Aashay's eyes were filled with fear on hearing this from his Aunt. Mithila asked him about the worst day of his life. This... changed his emotionless face. Mithila understood that something serious had happened to him. Something that turned a cheerful kid into the one sitting in front of Mithila.

What was it? What was 'trapped' in his mind which Mithila was trying to unlock?