IF - Then statement

Hi guys,
First, I would like to tell you that this example is not for English but for Arabic
This code I want to do the following:
- Search once at each hotkey press
- If the word is finished with a letter M delete the letter and write instead letter N.
- If the word ends with a letter N, delete the letter and write instead a letter M.
I do not know well using the IF - Then statement
Please help me

Code:

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Sub findend()
    Selection.Find.ClearFormatting
    Selection.Find.Replacement.ClearFormatting
    With Selection.Find
        .Text = "[nm]>"
        .Replacement.Text = ""
        .Forward = True
        .Wrap = wdFindContinue
        .MatchWildcards = True
    Selection.Find.Execute
    With Selection
        If Selection.Find.Found = n Then
          Selection.TypeText Text:=m
    Else
      If Selection.Find.Found = m Then
            Selection.TypeText Text:=n


End If
End Sub

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Any help would be greatly appreciated.

Code:

---

Sub findend()
With Selection.Find
  .ClearFormatting
  .Replacement.ClearFormatting
  .Text = "[nm]>"
  .Replacement.Text = ""
  .Forward = True
  .Wrap = wdFindContinue
  .MatchWildcards = True
  .Execute
End With
If Selection.Find.Found = True Then
  Selection.Text = Chr(109.5 - ((Asc(Selection.Text) = 109) + 1) / 2)
End If
End Sub

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