When logging into Minecraft, you can fail. If you fail too many times, you get IP banned for apparently, 24 hours. On my case, I have been banned for around 4-5 days. Apparently I was IP banned forever because I failed to enter my correct login credentials whilst trying to play Minecraft? Please let me know if there is already a fix to this bug, or if there ever will be a fix.
(There isn't anything about this topic on the Mojang support website)