Get value of one column based on value of two OTHER columns, then change column on another worksheet

Question

I have a workbook with three worksheets. I need to change the value in column K(row) on workbook B with the value of column CF(row) from workbook A based on a criteria (index?) of columns A and C on Workbook A and columns B and D on worksheet B. That is, these worksheets have the data in a DIFFERENT ORDER, one cannot simply loop through and copy over. I need to find the Row number of the CF(row) in worksheet A where the worksheet A and C columns are the same as the worksheet AB and D columns.

PsuedoSQL

UPDATE 
    Worksheet B
SET
    Worksheet B.K = Worksheet A.CF
FROM
    Worksheet A
WHERE
    Worksheet A.B = Worksheet B.B

Select from Worksheet A, column CF WHERE AA AND AC is equal to worksheet BB and BD AND SET Worksheet BK(Row) to Value worksheetA.CF(row)

The code I have is a look up that finds the LAST column with the matching text on worksheet A Column A, without any index or mapping.

Public Function FindPnum(keyword As Variant) As Variant
    Dim ws As Worksheet
    Dim rng1 As Range
    Dim rng2 As Range
    Dim tRow As Long
    Dim tCol As Integer

    Set ws = Sheets("Data")
    Set rng1 = ws.Cells.Find(keyword, ws.[b2], xlValues, , xlByRows, xlPrevious)
    Set rng2 = ws.Cells.Find(keyword, ws.[b2], xlValues, , xlByColumns, xlPrevious)

    If Not rng1 Is Nothing Then
        FindPnum = Cells(rng1.Row, rng2.Column).Address(0, 0)
    End If

End Function

Answer 1

Here try this

Sub pair()
Dim r, r2, found
r = 8
r2 = 2
found = False
Application.ScreenUpdating = False
Sheets(2).Activate
Do Until Len(Cells(r, 2).Value) = 0
Do Until Len(Sheets(1).Cells(r2 + 1, 2).Value) = 0 Or found = True
    If Sheets(2).Cells(r, 2).Text = Sheets(1).Cells(r2, 2).Text Then
        If Sheets(2).Cells(r, 11).Value <> 0 Then
            Sheets(2).Cells(r, 11).Value = Sheets(1).Cells(r2, 84)
        End If
        found = True
    Else
        r2 = r2 + 1
    End If
Loop
r2 = 2
r = r + 1
found = False
Loop
Application.ScreenUpdating = True
End Sub

I think this should do it.