Isso é útil Trecho:
At the grub prompt try these commands:
set pager=1
ls
Now, suppose the output of ls is: (hd0) (hd0,msdos2) (hd0,msdos1), in order to find the linux root filesystem run:
ls (hd0,1)/ which should give you all the files/folders in / such as bin/ boot/ cdrom/ dev/ etc/ home/ lib/ etc.
Once this is done continue with:
set root=(hd0,1)
linux /boot/vmlinuz-3.13.0-29-generic root=/dev/sda1
initrd /boot/initrd.img-3.13.0-29-generic
boot
Of course replace vmlinuz-3.13.0-29-generic and initrd.img-3.13.0-29-generic with what you find in your /boot
/dev/sda1 is the location of the root system. You may have to change it if /dev/sda1 did not work.
OU TAMBÉM:
Run those commands
grub> linux (hd0,1)/vmlinuz root=/dev/sda1
grub> initrd (hd0,1)/initrd.img
grub> boot
Replace hd0 with your hdd number and /dev/sda1 with your partition holding the /boot mainly the dafult will work if you don't have more than one hdd and with default installtion
When you can boot again you shoulf fix your problem
sudo update-grub
Aqui está outro = > repair-grub2-when-ubuntu-wont-boot /
E aqui = > repair-and-reinstall-grub-boot-loader-in-ubuntu /