Stuck On Class Selection...

I seemed to have gotten stuck on the class selection screen. Unfortunately, I cannot post an image because I don't have enough posts, but I DO know that I'm just staring at blank darkness with the message about needing the resource pack or the game won't make sense (but ironically, I have the resource pack), plus I can't use /class. So, what do I do now? I've just started playing and this happened.

 

* This thread has received 1 bump. Total bumps has increased to 1.