i don’t know that whether my question is from modern physics or not.

but my question is so simple and that is:

from where does the earth get its gravitational force?

@ archana 
gravitation is a property of object which is embeded in mass , if something have mass , then it will attract every other thing that are having the mass. 
now , scientist ave come forth with an unproved and undiscovered particle known as GRAVITON , which is resonsible for gravitational force . 
and recently we have HIGGS BOSON , which will explain why a particle have mass . 
HOPE IT CLEARS 

ALL THE BEST ..

The answer depends on which theory of physics you choose to believe in. To explain in layman’s terms ,

If u believe string theory , gravity is caused by the yet undiscovered hypothetical particle known as graviton.

If u believe quantum theory , gravity is caused by the bend in space-time continuum caused by the body having masses.

One thing to be noted is that the GRAVITON IS NOT YET DISCOVERED and it is absolutely not valid for quantum mechanics as it does not satisfy energy equations when subjected to lengths such as plank’s length. Graviton can only “exist” in string theory where particles are replaced by small strings.