Ok, I had to find where the keywords list was and restore it to a previous version. It's called Adobe Bridge Keywords.xml
Mac: (username)/Library/Application Support/Adobe/Bridge/
Windows: Cocuments and Settings(username)Application DataAdobeBridge
I have Windows and was able to right click and restore a previous version, restart Bridge, and it fixed my problem. Alternately you could check your other backup system.
Good luck! Luckily all your tags are in the metadata, so it's just the list itself that's missing.