How to check if a selected row in a datagridview is empty(has no item) C#

.Cells is a collection of DataGridViewCell objects.

You need to iterate through that collection & test each cell to see if it has a value...

if (currentRow.Cells.Count > 0) 
{      
   bool rowIsEmpty = true;    

   foreach(DataGridViewCell cell in currentRow.Cells)    
   {
      if(cell.Value != null) 
      { 
          rowIsEmpty = false;
          break;
      }    
   }

   if(rowIsEmpty)
   {
       MessageBox.Show("Select a non null row"); 
   }
   else
   {
       //DoStuff
   }
}

Another method to check if a new empty row is selected perhaps

if(dataGridView.CurrentRow.Index == dataGridView.Rows.Count -1)
{
    //you selected a new row
}