Ubuntu is cool but not if you don’t know what went wrong. Recently I made some changes which caused the Ubuntu logo to disappear (Symbol with circle animation). The logo doesn’t appear anymore while booting or shutting down. The only thing which appear on booting and shutdown is 4 dots which change color (red & white).
I have no idea of what I possibly could have done wrong.
Here are my questions:
What is the main reason of such problem? Can I undo the changes and put the logo back?