I am using Ubuntu 16.04. Single OS boot. After implementing the instructions given in https://askubuntu.com/a/362998 to rectify Ubuntu logo appearance during grub boot loading, I find my system unable to boot. It is stalled in a purple screen after grub2 menu stage.
I have gone through the instructions of this website to manually boot up from grub but nothing happens after I issued the boot command.
How do I get grub to correctly boot my system in grub?
How do I correct the /etc/default/grub file, example to return it to the original state and perform update-grub and update-initramfs at grub prompt?