in my catia v5 R21, the drafting workbench is invisible; but it shows the workbench is active . please help me

I want to do drafting , but from a couple of days I am in troubling . Because my drafting workbench( the white page in which the object changed into 3d to 2d) doesn't show, when I am going to do something then may be I clicked something wrong and it(the white page) has lost. but what exact I clicked, that skipped the mind. So I am really disappointed. Hope I will overcome soon through getting help. by the way, sometimes it shows me a " draw errors" . I was trying to do according to message( may be I wasn't right way). for convincing I added the pictures . please help me by figuring out. Thanks in advance!!!