Thanks a lot. you people help me. I involved myself in study from last few hours and I'm feeling much better now. I have a goal, I have to appear in a competitive exam, I required a lot of hard work to scored good in it. I don't know what is happening in my mind. It is only one thing that is disturbing me, I'm sorry I can't share as it is personal. That thing is disturbing me again and again. I 'm just trying to be normal and trying to control my brain not to pay attention towards it. I'm trying to make myself busy in studies to divert my brain attention. It is very difficult but still I'm trying. I have to keep trying because that thing is just getting on my nervous and I'm thinking that I will  become mad because of that. I have to remove it from my brain if I want to happily.