Thanks for the replies, I got it all figured out. I have NO idea what it actually was (I'm assuming just some sort of random glitch). I was down in my basement, where I have no service (yet this hasn't happened before). After I came back upstairs and had full service, the problem still persisted. Eventually it prompted me for my voicemail password, yet when I typed it in, it told me that it wasn't the right password. I eventually just reset my password (called 611, blah blah blah) and it reset, voicemails came back, etc. Weird...
Thanks anyways!