I have owned minecraft since it was a mojang program before microsoft took over. I was playing Java edition yesterday. I try to log in to minecraft and can only play the demo version.

I am trying to log into Minecraft but am unable to do so.  I played yesterday, but today I try and get a notice that I can get both the minecraft Java edition and the minecraft for windows edition at the same time.  I already have Java Minecraft and do not have a windows computer.  I play on a linux PC.  Why can I not log into minecraft?  It will allow me to play in demo mode but not regular game play.