Here is THE Rescue Disk that you should keep close to your computer !
- runs automatically Boot-Repair rescue tool at start-up
- also contains the OS-Uninstaller and Boot-Info tools.
- repairs recent (UEFI) computers as well as old PCs
HOW TO GET AND USE THE DISK:
(1) DOWNLOAD BOOT-REPAIR-DISK,
(2) Then burn it on a live-USB key via Rufus or Unetbootin. (do not burn it on CD/DVD if your PC came with Windows8/10)
(3) Insert the Boot-Repair-Disk and reboot the PC,
(4) Choose your language,
(5) Connect internet if possible
(6) Click "Recommended repair"
(7) Reboot the pc --> solves the majority of bootsector/GRUB/MBR problems