The grub command line is an inscrutable mystery to the uninitiated, but once you understand the basics, it’s not terribly difficult to boot your system and try to restore the normal boot process.

Two things appear wrong with your list of commands there. First, you need an initrd command. Second, you seem to have your partitions messed up. Here's what a proper sequence of GRUB commands ...

When Ubuntu changed to Grub 2 a couple of releases ago, it became significantly more difficult to set up multi-boot Linux systems. Most if not all Ubuntu derivatives are also using Grub2, and now ...

On the one hand, if you are familiar with GRUB commands, you can boot more less any device you want on the fly with the right incantation. On the other hand, it can be a pain to type in GRUB commands ...