I have installed Community Builder 1.2. with Joomla 1.5.7
Every works fine. But the Forgot Login? (i.e) Lost Postword and Lost Username was not working.
When I tried to check, It shows same page after entering the Send Password
Are you using an SEF extension, an ACL control extension... anything that changes CB or Joomla's core (hacks)? Have you tried with a default Joomla template? Did you make a CB Profile menu link?
I'm guessing it's a script issue with your template, but all of the above can cause problems.