Insert Row For Value Not Found

Maybe this:

Option Explicit

Sub ExampleInsertSort()
Dim OutPL As Worksheet, cell As Range, FindIt As Range
Dim NR As Long

Set OutPL = Sheets("Inventory_YARD")
NR = OutPL.Range("A" & Rows.Count).End(xlUp).Row + 1

For Each cell In Sheets("Working_Yard").Range("A:A").SpecialCells(xlCellTypeConstants)
    Set FindIt = OutPL.Range("A:A").Find(what:=cell.Value)
    If FindIt Is Nothing Then
        MsgBox "Item #" & cell & " Not Found. " & cell & " will be added to Inventory Yard"
        OutPL.Range("A" & NR) = cell
        OutPL.Range("C" & NR) = Cells(cell.Row, "B")
        OutPL.Range("D" & NR) = Cells(cell.Row, "Y")
        OutPL.Range("F" & NR) = Cells(cell.Row, "Z")
        NR = NR + 1
    End If
Next cell

Sheets("Inventory_Yard").Range("A:CC").Sort Key1:=Range("A1"), Order1:=xlAscending, Header:=xlGuess, _
        OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, DataOption1:=xlSortTextAsNumbers
End Sub