i have important block i want close the editor with password

i have important block i want close the editor with password

is that possible.

Lisp reactor maybe? Though it will only do so if you have the Lisp loaded. There's no "true" way of "protecting" your drawing through any type of programming (Lisp/VBA/ARX/DotNet). And certainly not for a block inside a DWG file. Even embedding VBA code into the DWG is circumventable, since the user could disallow running embedded macros.

The closest I know of is to protect your DWG file with a password: While in the SaveAs dialog, click the Tools drop-down (top-right). Then select "Security Options..." and type your password twice. After that you need to enter the password if you open that file, or open a file into which the secured DWG is xrefed. So it's an all-or nothing approach, i.e. you need the password to even view the DWG - not just a password for editing it. Thus in this case it doesn't help you too much, since you'll need to type the password to use your blocks - and if the password is typed, then it's editable as well. It's rather silly from ADesk to not include a modify password like you can do with PDFs.

An alternative way could be to use the standards checker to test if the DWG's blocks match those in a DWG file saved as DWS. At least then you could revert back to the original block definition after someone's "accidentally" edited your block.