Find string within word document

[lamnbj]

I have categories like:
a, Content.
a. Content:
a, Content:
I tried the following code with no success

Sub A123()
 
    On Error Resume Next
    
    Selection.Find.ClearFormatting
    Selection.Find.Replacement.ClearFormatting
    With Selection.Find.Replacement.Font
        .Bold = True
        .Color = wdColorBlue
    End With
    With Selection.Find
        .text = "(a[,\.] Noi dung)([.:])"
        .Replacement.text = "a) Noi dung"
        .Forward = True
        .Wrap = wdFindContinue
        .Format = True
        .MatchCase = False
        .MatchWholeWord = False
        .MatchAllWordForms = False
        .MatchSoundsLike = False
        .MatchWildcards = True
End With
    Selection.Find.Execute Replace:=wdReplaceAll
End Sub

Sorry my English is very bad. Thank you