@MojangSupport I haven't played minecraft for several years, I just uninstalled it because it kept crashing. When I went to reinstall it, it said I had to buy it again.
I'm sorry to hear that! When only the demo mode is accessible, this means that you're logging in with an account that does not contain a Minecraft profile/username attached. If you haven't yet, please visit https://help.minecraft.net/hc/en-us/articles/360029643892-Can-only-play-Minecraft-demo-Java-Edition- … for possible solutions. ^AS