A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
You can run the following macro (select the range first):
Sub ReplaceSpecial()
Dim cel As Range
Dim strVal As String
Dim i As Long
Application.ScreenUpdating = False
For Each cel In Selection
strVal = cel.Value
For i = 1 To Len(strVal)
Select Case Asc(Mid(strVal, i, 1))
Case 32, 48 To 57, 65 To 90, 97 To 122
' Leave ordinary characters alone
Case Else
Mid(strVal, i, 1) = " "
End Select
Next i
cel.Value = strVal
Next cel
Application.ScreenUpdating = True
End Sub