Get value from Row Command C#

//get value from linkbutton commandArgument isbn id

string isbn =Convert.ToString( e.CommandArgument);

Session["Inventory_ISBN"].ToString = isbn;

//get value from hidden filed

LinkButton btnedit = (LinkButton )(e.CommandSource);

HiddenField hf = (btnedit.Parent.FindControl("vendorid_hidden")) as HiddenField;

Session["Inventory_vendorid"] = Int32.Parse(hf.Value);///Datekey value