Yes, I have close all files and close Projects.
I have also uninstall and reinstall Lazarus IDE, even install Lazarus on another PC but all have the same problem.
After saving and existing the new Projects, when I try to open the Project again, the Object Inspector, Project Inspector and Message box all appear but not the Form and Source Editor.
I tried opening the Project from Open Project, Open Recent Project and from the File menu with the same problem.
Strange thing is it was working fine the day before when I go through a series of Lazarus tutorial.