c# Blob Mysql

this.files = OTB( ds.Tables[0].Rows[0]["files"]) ;

byte[] buff = ob as byte[];
MemoryStream ms =new MemoryStream ();
ms.Write(buff, 0, buff.Length);

FileStream pFileStream = new FileStream(@"E:\3.docx", FileMode.OpenOrCreate);
BinaryWriter w = new BinaryWriter(pFileStream);
w.Write(ms.ToArray());
//pFileStream.Write(buff, 0, buff.Length);

pFileStream.Close();

byte[]  b = File.ReadAllBytes (@"E:\2.docx");