Here's a summary of common steps to recover a missing GRUB bootloader:
1. **Boot from Live CD/USB**: If your GRUB bootloader has disappeared, you may need to boot your system from a live CD or USB drive with your Linux distribution.
2. **Mount Your Linux Partition**: Use the live environment to mount the partition where your Linux system is installed. Typically, this is done with a command like:
```bash
sudo mount /dev/sdXY /mnt
```
Replace `/dev/sdXY` with the actual partition where your Linux system is installed.
3. **Chroot into Your System**: Change your root directory to the mounted partition with the `chroot` command. For example:
```bash
sudo chroot /mnt
```
4. **Reinstall GRUB**: Reinstall the GRUB bootloader. The specific command depends on your Linux distribution. For Ubuntu, it's usually:
```bash
sudo grub-install /dev/sdX
```
For other distributions, you might use:
```bash
sudo grub-install /dev/sdX
```
Replace `/dev/sdX` with the drive where you want to install GRUB.
5. **Update GRUB Configuration**: Update the GRUB configuration file:
```bash
sudo update-grub
```
6. **Exit Chroot and Reboot**: Exit the chroot environment, unmount your partition, and reboot your computer:
```bash
exit
sudo umount /mnt
sudo reboot
```
These steps should help you recover a missing GRUB bootloader. However, the exact commands may vary depending on your Linux distribution, so be sure to refer to your distribution's documentation for more specific instructions.