Unable to make a mesh watertight

[sree9578]

I have obj file with polygon meshes
I am trying unwrap in blender , as the faces are not connected properly they are not distributed properly for UV coords.
I am also not able to do certain operation as the mesh is not watertight

I tried stitchborders form meshlab examples , still the mesh is not unwarped properly , guide me on steps to make mesh watertight , and unwrap properly

[sloriot]

Could you share the mesh?