Help Facebook for HTC Sense vanished


I just opened my phonebook to find no profile pictures beside my contacts, which are almost all linked to Facebook for HTC Sense. So I go to check my accounts, and somehow it no longer exists, at all. It doesn't show up under "accounts", and it's not on the list under "add accounts".

Facebook and Twitter for HTC Sense are still there, so it's not an issue related to Facebook or HTC Sense. This has never happened. I didn't update the software, or really alter anything. I had recently downloaded, tried, and subsequently deleted Regina Launcher and GO Launcher, but that's all I even altered on my phone.

Any ideas as to where it went and/or how to fix it would be much appreciated!