I would like to get complement of this path in Inkscape. So, black would become white and what is white would become black . Also, circular shape should be preserved. How to do this ?
In Inkscape, you can change the colours of the fills and strokes for any object to anything you want. Just select an object and change the stroke/fill attribute to the colour you want.
As for inverting the colours of an entire selection, simply select everything you want to invert and hit Filters > Colours > Invert
For the background, you can change it to white in document properties of Inkscape.