iMessage not signing in anymore - MacBook OS 10.9.5
A couple weeks ago, iMessage suddenly stopped syncing on my Mac. I noticed I could see previous conversations, but it looked as if I was "offline." I went into preferences and noticed that my Apple ID account wasn't logged in, so I typed in my password, and it just sat there with a spinning wheel doing nothing. I finally force quit the program, and upon opening it again, now I can't get past the main login screen. I type in my Apple ID and password, then a pop up box asks for my iMessage password, and upon typing it in and hitting Sign In, it just sits there on the main login screen yet again greyed out with the spinning wheel. It will sit there like this for hours if I let it, until I finally just force quit.
I've tried googling for similar issues but I'm not finding any good results. Anyone have any ideas?
To clarify, now that I can't get past the main login screen, I can't even access Preferences anymore. It's greyed out. Also my password is correct, I used it to create this post. I am not receiving any error messages whatsoever, just the spinning wheel that never tires.
MacBook, OS X Mavericks (10.9.5)