Why does my 3D Object become transparent When I click f12 the texture of my 3D object become like this. If I missed something please tell me. I'm newbie at motion track. It'll help a lot thanks :)
You enabled option shadow catcher.  The shadow catcher is a specific option, used typically on floor planes in order to 'catch' shadows from lighting within the scene. It is useful for integrating a rendered object onto a photographic background. 



You need to enable it on floor, not on object.

See also

How to use shadow catcher