It says i have to buy it when i bought it already

I bought the game over a year ago and i decided to switch the game to a different drive to save space on the other drive. I got to logging in i logged fine then it told me i could only play the demo unless buy the game which i went to the minecraft website and it told me I HAD IT I JUST HAD TO DOWNLOAD THE LAUNCHER AGAIN. so i downloaded the launcher, same results telling me i could only play the demo, tried two more times no changes. I need answers. I am growing tired of this.