I don't know what to do with my dissertation. I feel a great pressure. And now I'm really hesitate. I'm not sure what to do. Any ideas?

You are definitely not the first graduate student to not be sure what to do for their dissertation or thesis. It is a big project, and feeling stress/pressure is common. Talk to your professor, your adviser, and/or your peers to discuss possible ideas. You can even look online for topic ideas. Get started now, because the longer you wait, the closer to your deadline you will be, and the more stress you will feel. Good luck!