So there are a few features that have been disabled in AutoCAD 2012 and I have been waiting to post about them until I could find a solution. Well, I found a solution for one of them. This tip will also work on commands that have been “UNDEFINED” in previous versions of AutoCAD as well.
The command REDEFINE will make a command active/available after it has been UNDEFINED. Apparently, when AutoCAD gets rid of a command. They know people like me may have a hissy-fit and want the old command back. So what they do is just UNDEFINE the command so that it is no longer active. If you want to be mean to someone, you could run the UNDEFINE command and then it will ask what command you want to undefine…
To bring back the long-lost command:
REDEFINE <enter>
Enter command name to bring back <enter>
~Enjoy
PS – I used REDEFINE to bring back the command DSVIEWER
AutoCAD Tips 