How to boot from a bootable Recovery USB and recover the boot loader.
This is useful if you cannot boot your Operating System from disk.
Please note: You can follow this guide to create a bootable USB drive.
1 Cannot boot
If you can't access your operating system or its recovery menu, it can be repaired from a bootable USB drive.
Firstly, insert the USB drive and turn on your computer whilst repeatedly tapping the F7 key.
This will bring up the boot menu.
2 Boot Recovery USB
Use the arrow keys to select your USB drive and press enterto boot from it. You need to use the live mode of the USB. There are a few different terminologies used but typically it is Live, Tryor **Start.**On Ubuntu, the option to select is Try Ubuntu.
3 Check disk path
Open the GNOME Launcher and open Terminal.
To check the path of the disk, type in the below command:
sudo fdisk -l | grep nvme
4 Partition of disk
This will reveal the partition of the disk that needs mounting.
5 Mount partitions
Most installs will only have the 2 partitions shown.
Run the below commands to mount them:
mount /dev/nvme0n1p2 /mnt
mount /dev/nvme0n1p1 /mnt/boot
6 Enable network
Depending on what you need to do in the recovery mode, you may want to enable internet access with:
sudo cp /etc/resolv.conf /mnt/etc/resolv.conf
7 Connecting to installation
From here, we need to chroot into the disk with:
sudo chroot /mnt /bin/bash
8 Connected to installation
This will take you to a terminal window running as rooton your SSD.
9 Ready to diagnose
From here we are ready to perform further diagnostics on the installation.
- fsck - Check file system
- GRUB Repair - Update bootloader
- dpkg - Repair broken packages
See further guide on using recovery mode