Boot Repair Disk - A rescue disk that includes the Boot Repair tool
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
- DOWNLOAD BOOT-REPAIR-DISK
- 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)
- Insert the Boot-Repair-Disk and reboot the PC,
- Choose your language,
- Connect internet if possible
- Click "Recommended repair"
- Reboot the pc --> solves the majority of bootsector/GRUB/MBR problems

Good luck!