You can hold Shift at the very beginning of the boot process to see it.) If you do see the GRUB boot menu, you can use the options in GRUB to help repair your system.Select the “Advanced options for Ubuntu” menu option by pressing your arrow keys and then press Enter. (recovery mode)” option in the submenu and press Enter.Ubuntu should find your existing installation and give you a “Reinstall Ubuntu” option.When you perform a reinstall, the installer will keep all your personal files and settings.You’ll find the Ubuntu drive under Devices in the sidebar.
GRUB can also boot Windows for you, so you’ll still be able to boot into Windows after you install GRUB.It will even keep your installed software packages, if possible.The Reinstall option will wipe away all your system-wide settings and return them to their defaults, but that should fix problems that misconfigured system settings could cause.You can use an Ubuntu installation disc or USB drive to do this.Boot into the USB drive and use the the Linux system to repair GRUB.The GRUB2 boot loader will appear and boot Ubuntu normally.(GRUB2 is hidden by default, so you may just see Ubuntu boot.In dual-boot situations, you should generally install Linux on a computer after you install Windows.RELATED: If you can’t access GRUB, you’ll need to repair it.Select this option and continue through the process to reinstall Ubuntu on your computer.The installation process will also reinstall the GRUB2 boot loader along with Ubuntu, so it will also fix any GRUB issues.