using System.Collections.Generic;
  private string GetSearchPacketReqId(string pathofbasefolder, string filename)
    {
        try
        {
            string strFileName = "";
            string strReqId = filename + ".xml";
            Stack directoryStack = new Stack();
            directoryStack.Push(baseDir);

            while (directoryStack.Count > 0)
            {
                string currentDir = directoryStack.Pop();

                foreach (string fileNamePath in Directory.GetFiles(currentDir, "*.*"))
                {

                    StringBuilder strBuilder = new StringBuilder();
                    strBuilder.Append(fileNamePath);
                    strBuilder.Remove(0, currentDir.Length + 1);
                    if (strReqId == strBuilder.ToString())
                    {
                        //XML file name that you search
                        strFileName = fileNamePath;
                        return strFileName;
                    }
                }

                foreach (string directoryName in Directory.GetDirectories(currentDir))
                {
                    directoryStack.Push(directoryName);
                }
            }
            return strFileName;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }