Some time i get a pain in my chest like some thing heavy is sitting on me what can ot be ?

It depends: There are multiple issues that can cause the chest pain you're describing, perhaps the most important being coronary artery disease (blocked artery or arteries of the heart). A formal evaluation by your primary care physician and possibly a cardiologist will be helpful. I would not allow a recurrent pain in the chest to persist for long without explanation.

Heart?: Could be your heart. Have it checked out soon.