呵呵,最近写的一个程序也许能帮到你...
private string GetFileCopy(string fileName, string dirName)
        {
            DirectoryInfo dirc = new DirectoryInfo(dirName);
           foreach (DirectoryInfo dir in dirc.GetDirectories())
            {
                string fSourceFile = dir.FullName + "\\" + fileName;
                if (System.IO.File.Exists(fSourceFile))
                {
                    return fSourceFile;
                }
                else
                {
                    getFile(fileName, dir.FullName);
                }
            }
           
            return "没有文件";
        }