Reinstall Grub to boot Ubuntu

Reinstall Grub to boot Ubuntu with Grub4DOSfind-set-root/boot/grub/core. imgkernel/boot/grub/core. if imgboot www.2cto.com has/boot partitions, change to find-set-root/grub/core. imgkernel/grub/core. after img is restarted, Grub4Dos will be automatically transferred to grub2. After ubuntu is selected from grub2 menu, run sudo grub-install/dev/sda on the terminal to mount grub to the mbr of the first hard disk, if you want to change the mbr of the second hard disk to sdb, the third hard disk to sdc, and so on. To install grub on the mbr of sda, sdb, or sdc, You need to determine the disk to be set as the boot disk according to your own situation, mount grub to the mbr of the hard disk.