All line integrals in the world are zero...? Using Stokes' theorem, the line integral of a vector field gives a surface integral of the curl of the vector field, and after that, if we apply Gauss' divergence theorem in that, it gives a volume integral of the divergence of the curl of that vector field. But we know the divergence of the curl of a vector field is $0$. … so how can it be possible? Where is the mistake??

Stokes theorem relates the line integral around a curve to a surface integral through an open surface.
The divergence theorem relates the surface integral through a closed surface to a volume integral. 
You cannot do what you are trying.
