W8.1 won't boot "Your PC did not start correctly", Startup Repair error : "root cause found: registry is corrupt"

Question

My PC (Windows 8.1, dual booting with Windows 10 Dev Preview) won't boot, every time I try it just goes to Automatic Repair which always fails.
Things I tried:

1. Safe mode doesn't work (goes to Automatic Repair).
2. sfc /scannow doesn't work (message: There is a system repair pending ...)
3. sfc /scannow /offbootdir=d: /offwindir=c:\windows didn't work either. (message: Windows Resource Protection could not perform the requested operation.)
4. I did chkdsk /r c: twice didn't find any errors.
5. Tried Startup repair with installation USB a couple of times, most recent one said "root cause found: registry is corrupt"
6. When I first tried System Restore I was able to see restore points (the latest restore point was a windows update of the 13th but it didn't let me restore saying that I need to enable the system protection, my PC stopped working on the 14th) but I can't see any restore points.
7. Refresh doesn't work. (message: There was a problem refreshing your PC. No changes were made)
8. bootrec /fixmbr, bootrec /fixboot, bootrec /rebuildbcd none of them worked.

I do have registry back ups, but I'm not sure how to do a restore if I can't go to safe mode. Is there anything else I should try before giving up and reinstalling?

Solution

I couldn't solve the problem so I reinstalled the OS. But I did a fresh install over the non-working W8.1 so that my stuff will be stored in Windows.old so that I can retrieve them later.

Comments

[JosefZ]

Could you check your boot disk mode in BIOS settings: IDE or AHCI mode? or RAID mode?

[MrT3chGuy]

@JosefZ Thanks for the reply. It says Native IDE.

[Mina Wissa]

Did you find a solution to this?, I have the same problem

[MrT3chGuy]

@MinaSamy No, not yet, I'm close though. I found a backup of my registry, but when I restored it, the blue loading Windows flashes then goes to automatic repair. I'll update the post if I find the solution.

[Mina Wissa]

Well, I had to do a fresh install, re partitioning the hard disk as in this video youtube.com/watch?v=xvoYCdHvJSc

[MrT3chGuy]

@MinaSamy I see, I'll do that too if I can't get it to work.

[Rob Watts]

Sounds like the same situation I found myself in when I asked Is it possible to enable System Protection from the command prompt?.

[MrT3chGuy]

Thanks for the reply but I when I go to System Restore I don't see any restore points :(