I downloaded the new BB messenger and now i need to get the old version back.
Can anyone help me on this plz?

You posted in the Site Suggestions News and problems section, I'll move this post to the 8520 section of the forum

For your question, delete the updated BBMessenger and then load the OS for your device to your PC and run Desktop Manager > Application Loader and you should be prompted to install BlackBerry Messenger by CHECKING the box for it in the installer window.