This same exact thing happen to me. I have open chat (I can say anything including numbers) and I couldn't speak either. I never got reported, I didn't receive an email that said I was chat banned and the notice that would have said I was chat banned didn't appear so knew I wasn't chat banned. I can't remember what fixed it. I uses menu chat and that didn't work then I left the area I was in and then I could chat again. I guess it's just a weird glitch.
I could use the menu chat but was blocked from open chat. I logged off and reported it to customer service along with an explanation that I havent received any notifications of complaints etc. Then when I logged back in, I could talk.
Havent had any other problems with it... just weird bug.