You'll need to be a little more specific. What do you mean by "enable"?
Have you installed Reader? That should be all ther is to it.
some how my adobe reader has been uninstalled from my computer, it needs to be reinstalled, please, thank you
Go to http://www.adobe.com/ and click on the button that says "get ADobe Reader". Follow the instructions.
If you have any issues, come back and let us know what they are. Please be sure to include every detail.