Windows 10: BSOD and BAD_SYSTEM_CONFIG_INFO Error when booting

Been using Win10 for a year with no problems along with various other Linux partitions (grub). Normally when I bootup I'm using UEFI settings in the BIOS and Windows is one of the grub menu choices. Fine, that's all been working fine for many months.
Today I made a bone head move when trying to boot another OS from the USB drive in "legacy" boot mode instead of UEFI. A different boot (grub?) menu showed up that said "Windows 8" ... dunno if that was left over from my upgrade last year to Windows 10. Anyway, when I hastily selected it, as it booted it said something like "entering recovery"... or something like that. I realized it was wrong so I quickly rebooted to stop it.
Well now my system only gives BSOD and "BAD_SYSTEM_CONFIG_INFO" when I choose to boot Windows 10 under UEFI. So something got hosed. I've tried all the normal recovery options presented by Windows 10 but nothing works. My Linux partitions are all fine - I'm booted and using it right now. So what are my options (easiest first) for fixing my Windows Bootup?

Lenovo Ideapad G50-45 AMD 8GB notebook

Phew! Managed to fix it. As per a recommendation on another forum I went into the recovery options and opened up a command prompt window. Then I copied the replaced the Registry files with the backup files - by copying all files from C:\Windows\System32\config\RegBack to C:\Windows\System32\config after backing up the originals (I copied all the files in C:\Windows\System32\config to C:\temp\backup).
Then I restarted and it booted up and ran fine... with no errors reported at all. woot!

Now, I wonder what I've lost by using these backup registry files. The difference between them are as follows:

New backups now in place:
05/26/2016 05:58 PM 233,472 DEFAULT
05/26/2016 05:58 PM 32,768 SAM
05/26/2016 05:58 PM 28,672 SECURITY
05/26/2016 05:58 PM 73,424,896 SOFTWARE
05/26/2016 05:58 PM 11,796,480 SYSTEM


my original (broken) ones:
06/16/2016 07:04 PM 42,991,616 COMPONENTS
06/19/2016 11:35 PM 73,662,464 SOFTWARE
06/19/2016 11:35 PM 32,768 SECURITY
06/19/2016 11:35 PM 262,144 DEFAULT
06/28/2016 10:40 PM 12,582,912 SYSTEM

how the f do you delete a dup post? dam