There's no such thing as "LibBabble-3.0". Read the error message more closely to find out which Babble library is actually missing, and then you can solve your problem by downloading that library as a standalone.
After a quick look it appears LibBabble-Spell-3.0 is the only babble lib AutoBar uses. You'll need to download that. I'd suggest using WowAceUpdater to make sure you have up-to-date and complete packages for each of your Ace addons.
I had a similar problem to this. Autobar just wouldn't work anymore all of a sudden. What I did was to remove all files related to Autobar, including saved variables, and then reinstalled it. Then it worked again. :)