Its not that difficult Arun. When did you start flying Quads and what mode are flying them at?
In Beginner mode or Low rates, the yaw is not very responsive and hence can be difficult to take tight turns required for a indoor circle. Try it in Expert mode or High rates and see if it helps.
You should have bought a protection cover like this -
CX10 Protection Cover which would have enabled you to keep flying even if you bump the walls when practicing circles.
Just Practice, Practice, Practice! You'll get the hang of it sooner than you think :D