Presentation presentation = new Presentation(@"C:\Users\Administrator\Desktop\sample.pptx", FileFormat.Pptx2010);

StringBuilder sb = new StringBuilder(); 

 foreach (ISlide slide in presentation.Slides)
  {
  foreach (IShape shape in slide.Shapes)
  {
   if (shape is IAutoShape)
   {
   foreach (TextParagraph tp in (shape as IAutoShape).TextFrame.Paragraphs)
   {
    sb.Append(tp.Text + Environment.NewLine);
   }
   }
  }
  }

 File.WriteAllText("target.txt", sb.ToString());
 Process.Start("target.txt");

Presentation ppt = new Presentation();
 ppt.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pptx");

 for (int i = 0; i < ppt.Images.Count; i++)
 {
 Image image = ppt.Images[i].Image;
 image.Save(string.Format(@"..\..\Images{0}.png", i));
 }

Presentation PPT = new Presentation();
PPT.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pptx");

int i = 0;
foreach (IShape s in PPT.Slides[2].Shapes)
{
 if (s is SlidePicture)
 {
 SlidePicture ps = s as SlidePicture;
 ps.PictureFill.Picture.EmbedImage.Image.Save(string.Format("{0}.png", i));
 i++;
 }
 if (s is PictureShape)
 {
 PictureShape ps = s as PictureShape;
 ps.EmbedImage.Image.Save(string.Format("{0}.png", i));
 i++;
 }
}