ممنون از شما .
مشکل من حل شد . البته با شئی word !
strSrcFile = "c:\utf8.txt"
strDstFile = "c:\ansi.txt"
strFind = "~"
strReplace = ","
objWord = CreateObject("Word.Application")
RC = objWord.Documents.Open(strSrcFile)
objWord.Selection.Find.Text = strFind
objWord.Selection.Find.Replacement.Text = strReplace
objWord.Selection.Find.Forward = 1
objWord.Selection.Find.Format = 0
objWord.Selection.Find.MatchCase = 0
objWord.Selection.Find.MatchWholeWord = 0
objWord.Selection.Find.MatchWildcards = 0
objWord.Selection.Find.MatchSoundsLike = 0
objWord.Selection.Find.MatchAllWordForms = 0
RC = objWord.ActiveDocument.SaveAs(strDstFile,2)
RC = objWord.Application.Quit