Advantage
- you can give/show contents for only selected users(the users that you give the password)
Problems
- You cann't unlock/open the locked contents in Admin or Moderator power,
- You cann't use more than one locking content at one post/message.
Requirements
- users must not have a power to delete own messages on forum.
Let start
First go to in MIF in the first box remove::msg::and replace by this

and the quote button must have class and name value. add this on quote button tag

*it use to hide quote button when the content it is on locked,and to show when the content is unlocked.
Next on the top content for forum add this css

Finally add this Script at the bottom content for forum

How to use
when you create a topic add the content with lock bbcode like this [*lock=PASSWORD HERE] CONTENT HERE[/*lock] (remove * sign)