: Select Repair your computer > Troubleshoot > Advanced options > Command Prompt .
: Type these commands in order, pressing Enter after each: Hard Drive Mbr Repair Software
bootrec /rebuildbcd — Scans for installations and rebuilds the Boot Configuration Data. How Do I Fix the Master Boot Record (MBR)? : Select Repair your computer > Troubleshoot >
This is the most direct method and doesn't require downloading extra software if you have a Windows installation or recovery USB. Hard Drive Mbr Repair Software