How to apply 'for' loop for repetitive tasks in multiple column

Hi All,

I am new to VBA coding and would be great if anyone can help me with the below two points:

1. I have written a code however not able to put it into a for loop, so that i can stop rewriting the same code for multiple columns, secondly i am not able to add piece of code to replace single backslash with double backslash in the same code, below is the code i am using:

Dim addr As String
        
Sheets("ROM Catalog Collection").Unprotect

With Worksheets("ROM Catalog Collection")
Row2 = .range("C4").End(xlDown).Row
For i = 4 To Row2
 
If .Cells(i, "C").value <> "" Then
.Cells(i, "C").value = Replace(Application.Trim(.Cells(i, "C").value), "  ", " ")
End If
If .Cells(i, "C").value <> "" Then
.Cells(i, "C").value = Replace(Application.Trim(.Cells(i, "C").value), """", "'")
End If
If .Cells(i, "C").value <> "" Then
.Cells(i, "C").value = Replace(Application.Trim(.Cells(i, "C").value), "chr(151) or chr (150)", "-")
End If


Next i

End With

With Worksheets("ROM Catalog Collection")
Row2 = .range("D4").End(xlDown).Row
For i = 4 To Row2
 
If .Cells(i, "D").value <> "" Then
.Cells(i, "D").value = Replace(Application.Trim(.Cells(i, "D").value), "  ", " ")
End If
If .Cells(i, "D").value <> "" Then
.Cells(i, "D").value = Replace(Application.Trim(.Cells(i, "D").value), """", "'")
End If
If .Cells(i, "D").value <> "" Then
.Cells(i, "D").value = Replace(Application.Trim(.Cells(i, "D").value), "chr(151) or chr (150)", "-")
End If
Next i

End With

With Worksheets("ROM Catalog Collection")
Row2 = .range("G4").End(xlDown).Row
For i = 4 To Row2
 
If .Cells(i, "G").value <> "" Then
.Cells(i, "G").value = Replace(Application.Trim(.Cells(i, "G").value), "  ", " ")
End If
If .Cells(i, "G").value <> "" Then
.Cells(i, "G").value = Replace(Application.Trim(.Cells(i, "G").value), """", "'")
End If
If .Cells(i, "G").value <> "" Then
.Cells(i, "G").value = Replace(Application.Trim(.Cells(i, "G").value), "chr(151) or chr (150)", "-")
End If
Next i

End With

With Worksheets("ROM Catalog Collection")
Row2 = .range("H4").End(xlDown).Row
For i = 4 To Row2
 
If .Cells(i, "H").value <> "" Then
.Cells(i, "H").value = Replace(Application.Trim(.Cells(i, "H").value), "  ", " ")
End If
If .Cells(i, "H").value <> "" Then
.Cells(i, "H").value = Replace(Application.Trim(.Cells(i, "H").value), """", "'")
End If
If .Cells(i, "H").value <> "" Then
.Cells(i, "H").value = Replace(Application.Trim(.Cells(i, "H").value), "chr(151) or chr (150)", "-")
End If
Next i

End With

(continued for 8 more columns..)

2. Another question i have is, if in a particular cell i have 2 values with '.' (dot) separator i can replace it with ',' (comma) or if there are multiple spaces i can trim it to one space however, if there is 1 value in the same cell its still replacing it with ',' as per the above rule, as for single value i just want to trim with single space or remove the dot if any.

EX:

'ABC. DEF' should get replaced as 'ABC,DEF' by removing space and replace the dot'.' with comma',' (below code is working till here)
if it's only 'ABC .' its converting it as 'ABC,'
What amendment i can make here so it becomes only 'ABC' (trim the space and remove any special character) in case of single value in that cell.

Using the below code:

Sub AppMnemonics()
Dim c As range, lr As Long
Sheets("ROM Catalog Collection").Unprotect

lr = Cells(Rows.Count, "J").End(xlUp).Row
With Worksheets("ROM Catalog Collection")
    lRow = .range("J4").End(xlDown).Row
    
    For i = 4 To lRow
    If .Cells(i, "J").value <> "" Then
                .Cells(i, "J").value = WorksheetFunction.Trim(.Cells(i, "J").value)
                End If
    Next i
End With
For Each c In range("J4:J" & lr)

    c.value = Replace(Application.Trim(c), ".", ",")
    c.value = Replace(Application.Trim(c), " ", "")
Next c

Thanks!