Says I have not bought minecraft

I have bought the full version of Minecraft a few months ago and have been playing on it for a while now. Then one day my internet seemed a bit slow and Minecraft kept logging me out, so I decided to shut down Minecraft and re open it again. But instead of logging me in Minecraft Launcher opened up saying that I could only play the Demo version and that if I wanted to play the full Version I had to Buy it AGAIN! I tried everything I could starting by logging out and back in , then changing my password and re-installing Minecraft launcher. None of these worked and the scenarios on the "Having trouble accessing your account page" did not match my problem. I just want to play Minecraft with my friends again please fix my problem.