[Solved]-d3 force links not connecting-d3.js

You have to supply the link records to the link force.

var link_force =  d3.forceLink(links_data)
          .id(function(d) { return d.name; })
          ;

Have a look at your CSS

.link {
    fill: #FFFFFF00;
}

Better is

.link {
    fill: none;
}