[Gajanan Dongardive]

Showing demo presentation when phone in charge. And replace all my contacts with some demo contact. It shows Lumia retail Demo, MS Demo 1, 2 ,3,4 and getting calls from unknowns contacts(Demo contacts ..Verified it). getting update of demo frequently.

Is there any settings i need to change?

[pankaj981]

Nope, you actually have a device running demo firmware or an actual store demo device. If you bought it new then replace it, demo units are not supposed to be sold as new. If you bought from a a 3rd part, return it if possible. If you want to live with it then better flash it to a retail ROM, the demo firmware will not let you use it as a phone and reset everytime