Minecraft only lets me play demo?

So, I brought this game way back. I don't even remember when, probably 2011-2012. I played it a lot, but slowly started to stop a few months ago. I haven't played it for about 2 months. I decided to go back today and play a bit, but when I opened it it asked for my account password and username. I forgot my password so I did the whole "forgot your password?" stuff and changed my password. I logged in to my account, but now its saying I can only play demo. I'm confused and a bit frustrated. I've had the game for years now, I've changed the password a few times in the past so I don't think its that, and I'm just pissed.