How do I reinstall Windows Messenger?

From: Bob (anonymous_at_discussions.microsoft.com)
Date: 02/28/04 

Date: Sat, 28 Feb 2004 08:10:22 -0800

I disabled Windows Messenger by following the steps given
on this group. Now my employer is asking all of us to use
it. How do I get it back without having 2 of them? I
don't know if the first one was removed or just disabled.