MacroExcel

Sub FindAndBold()
    Dim sFind As String
    Dim rCell As Range
    Dim rng As Range
    Dim lCount As Long
    Dim iLen As Integer
    Dim iFind As Integer
    Dim iStart As Integer

    On Error Resume Next
    Set rng = ActiveSheet.UsedRange. _
      SpecialCells(xlCellTypeConstants, xlTextValues)
    On Error GoTo ErrHandler
    If rng Is Nothing Then
        MsgBox "There are no cells with text"
        GoTo ExitHandler
    End If

    sFind = InputBox( _
      Prompt:="What do you want to BOLD?", _
      Title:="Text to Bold")
    If sFind = "" Then
        MsgBox "No text was listed"
        GoTo ExitHandler
    End If

    iLen = Len(sFind)
    lCount = 0

    For Each rCell In Selection
        With rCell
            iFind = InStr(.Value, sFind)
            Do While iFind > 0
                .Characters(iFind, iLen).Font.Bold = True
                lCount = lCount + 1
                iStart = iFind + iLen
                iFind = InStr(iStart, .Value, sFind)
            Loop
        End With
    Next

    If lCount = 0 Then
        MsgBox "There were no occurrences of" & _
          vbCrLf & "' " & sFind & " '" & _
          vbCrLf & "to bold."
    ElseIf lCount = 1 Then
        MsgBox "One occurrence of" & _
          vbCrLf & "' " & sFind & " '" & _
          vbCrLf & "was made bold."
    Else
        MsgBox lCount & " occurrences of" & _
          vbCrLf & "' " & sFind & " '" & _
          vbCrLf & "were made bold."
    End If

ExitHandler:
    Set rCell = Nothing
    Set rng = Nothing
    Exit Sub

ErrHandler:
    MsgBox Err.Description
    Resume ExitHandler
End Sub