The Model doesn't appear when rendering....? UPDATE I'm sorry for my last question I wasn't know what I have to upload to make my question clear also I'm a beginner ...

I have finish my tracking then try to render using F12 the result as shown in the screenshot
it show only a shadow                                                                          



and as you asked I will upload .blend file 

https://www.mediafire.com/?x5d1n0z99iufle3

please help me with this problem ..Thank You
I believe it is because you are using the multiply node in the compositor. The multiply node is kind of like mixing two things in a way so that the brightness value is the factor (sorry if this doesn't make sense, there are lots of better explanations out on the internet). When you multiply the Suzanne and the movie clip, since the suzanne is white, it doesn't show through. 

I made a few changes to your composite setup. First I checked the Object Index pass under the Render Layers tab. I assigned Suzanne a pass index of 1 and the ground a pass index of 2. I wasn't able to get a good picture so I'm attaching a link to the .blend file but essentially, I masked out everything but the Suzanne and then used the mask to mix the head back in if that makes sense. Here's what the render looked like. Of course you would replace the color grid with your video.





Hope this helps! Good luck!