Copy columns based on the autofiltered column, then paste value only to that autofiltered column - excel

Question

I want to filter column B based on values like "Unknown", then filter L column to have un-null values. copy the L column.
Paste values only to the column B.
Before:
ColumnB ..... Column L
1 ..... a
2 ..... b
Unknown.c
3.......d
Unknown.e
Unknown.
After
1 ..... a
2 ..... b
c.......c
3.......d
e.......e
Unknown..
Set r1 = Range("B:B").SpecialCells(xlCellTypeVisible)
Set r2 = Range("L:L").SpecialCells(xlCellTypeVisible)
Set myMultipleRange = Union(r1, r2)
Application.ScreenUpdating = False
sh1.Range("B:L").AutoFilter
sh1.Range("B:B").AutoFilter Field:=1, Criteria1:="Unknown", Operator:=xlFilterValues
sh1.Range("L:L").AutoFilter Field:=11, Operator:=xlFilterValues, Criteria1:="<>"
LstRw = sh1.AutoFilter.Range.Columns(1).SpecialCells(xlCellTypeVisible).Cells.Count - 1
If LstRw <> 0 Then
myMultipleRange.FillLeft
End If
The above code will copy and paste including the format.

Answer 1

Copy/paste in a filtered table is no good idea, because it inserts data continously even in hidden rows and messes up your data.
I recommend the following:
Filter data
Loop through all visible cells and copy the data row by row
If the following data is given …
… and you want to replace unkown with the data in column L, you can do the following:
Option Explicit
Public Sub FilterAndCopy()
Dim ws As Worksheet
Set ws = ThisWorkbook.Worksheets("Tabelle1")
'Filter data
ws.Range("B:B").AutoFilter Field:=1, Criteria1:="Unknown", Operator:=xlFilterValues
Dim LastRow As Long
LastRow = ws.Cells(ws.Rows.Count, "B").End(xlUp).Row
Dim DestinationRange As Range
On Error Resume Next 'next line throws error if filter returns no data rows
Set DestinationRange = ws.Range("B2", "B" & LastRow).SpecialCells(xlCellTypeVisible) 'find visible cells between B2 (exclude header) and last row in B
On Error GoTo 0 'always re-activate error reporting!
If Not DestinationRange Is Nothing Then 'do it only if there is visible data
Dim Cell As Range
For Each Cell In DestinationRange 'copy each value row wise
Cell.Value = Cell.Offset(ColumnOffset:=10).Value 'column L is 10 columns right of B
Next Cell
End If
End Sub

Answer 2

Alternative solution - simply go through each cell in column B and replace "Unknown" with a respective value in column L.
Sub foo()
Dim lngLastRow As Long
Dim rngCell As Range
With Sheet1
LastRow = .Range("B" & Rows.Count).End(xlUp).Row
For Each rngCell In .Range("B1:B" & LastRow)
If rngCell.Value = "Unknown" Then
rngCell.Value = .Range("L" & rngCell.Row).Value
End If
Next rngCell
End With
End Sub
P.S. Make sure to replace With Sheet1 statement with a relevant sheet name/code.