Could anyone help me to choose a unique topic for my research in literature or any interesting topic? I will be thankful.
We definitely need more information than you have provided. For example, what type of literature? American, British, World, or a specific country's literature? Also, what level? Are you a high school student, a college student? Are you majoring in literature? We need to know what level you are on in order to be able to suggest appropriate research topics.
Another thing that would be helpful to us if we are to help you is knowing what your interests are. Do you enjoy fiction? Poetry? Is there a particular time period in literature that interests you? All literatures are divided into periods. Some examples are Romantic, Classic, Realistic, Naturalistic, Modern, Ancient - and many, many more. In British literature, for example, if you were interested in the Elizabethan Period, in which Shakespeare wrote, there would be all sorts of specific research topics you could explore.
Also, what authors interest you? There is nothing worse than doing research on a topic that is not of interest to you. Which authors have you read and enjoyed? It is best to choose one of them if you are going to focus on one author. For example, if you enjoy the novels and short stories of Flannery O'Connor, an American writer, you could research how she uses her religious faith in her themes. Or, a current topic that needs lots more research is American diasporic writers - those writers that come to America from other countries and write a unique form of fiction that reveals not only their native cultures but also shows how they are integrating, or not integrating, into their adopted culture. You could also choose two different authors and show how they treat the same subject - for example how do Ernest Gaines and Maya Angelou deal with racism in their literature? You might want to explore certain kinds of themes in literature, such as feminism. You really need to narrow things down in order for us to help you.
If you could re-post your question and answer some of these specifics, perhaps we could help you better.