"error file not found." and "grub rescue

On deleting a partition on a Linux Mint 14 box I got:

error file not found.
grub rescue > _

Running the grub-rescue disk fixes the problem. Better yet is to use Boot Repair to fix the bootloader.

• Boot Ubuntu from a LiveCD or Live USB.
  
• Connect to the internet.
  
• Open a terminal, and add the Boot Repair PPA:

 sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update

• Install and run Boot Repair:

sudo apt-get install -y boot-repair && boot-repair

If you get these errors:

Err http://ppa.launchpad.net trusty/main amd64 Packages
  404  Not Found
W: Failed to fetch http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu/dists/trusty/main/binary-amd64/Packages  404  Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.

then try:

sudo vi /etc/apt/sources.list.d/yannubuntu-boot-repair-trusty.list

and change trusty to saucy

A good command for finding your partitions is:

sudo blkid