I am a new user of Ubuntu. I follow all the instructions to install it. It seemed to be successful. And I had saved some files in it. Somehow, I don't really see the GRUB menu when I start Ubuntu again. Still, it shows me the menu of installation/try/defaults. When I choose default (since I've installed), it enters like normal, but the files that I'd saved earlier are missing. Everything is like "newly-installed", everything is just new. Does anyone know what happen?