How I can join circle when it is break at two points through break command. Please someone answer me.
Thanks.
 
 

please give me tips to join circle when it is break at two points by using break command in AutoCad2004

Try e.g. the PEDIT command and its Close option.

Explode the circle. The circle will now be 4 quadrants with nodes at the ends. Break the quadrants if you need to, then do the same for the circle segments you wish to add, snap the ends of the segments together, and the type PE at the command line and choose one of the segments and it will ask you if you want to convert it to a polyline. Say yes, and then it will offer you a bunch of choices to edit the polyline you just made. Choose "join" and select all the circle segments that you want to join, and hit enter.

The simplest method is pick the arc (partial circle)
type Join
enter
type close
enter
 
 

I have faster solution for you:
1. Visit http://www.cadaplus.com/downloads.php?lang=en
2. Download and install APlus plugin (it's free to use for 30 days)
 
Now you can join parts of circle with JJ command (Join into polylines) or close any arc with CARC command.
 
Hope that helps :)