Something, possibly malware, clobbered my boot drive. This is an HP laptop, I7, 8GB ram, 1TB hard drive (C: & D:recovery drive config), Windows 10 (current build). I have run every diagnostic and repair options built into HP and/or Windows 10 and all HW passes all tests. I have been able to boot via a USB recovery drive. Through command prompt utilities, it appears that everything on the drive is intact. It just won't boot. I have a recent backup, so I can - if necessary - reinstall Windows and then restore. I would much prefer to rebuild / fix the boot record. In my younger "DOS" days, I could do this easily, but technology has improved dramatically. There must be an easier way. Can someone give me a step by step guide to rebuilding the master boot record, please?