Problen with Object not appearing in render i don´t know what`s happenig why isn´t rendering but in the last proyect everything was fine. Hope someone can help.
The grey Background with the grid means, there is no Image to preview. You did not actually start a Render. You can start a Render in the Header via Render > Render Image or by hitting F12.

You probably used View Render or F11, wich displays the last Render (in this Case None).