windows 8 - How to unlock a Hard Drive and Refresh PC

I have Windows 8, and none of the metro UI apps were working, so I downloaded a registry fix from Microsoft. I ran it, and during that time I ran Windows Update. I restarted the PC, and after the boot screen with the Windows 8 logo, it never showed the lock screen, just a black screen.

I force restarted the computer several times, checking whether the problem still occured and it did. I attempted to fix this problem by running my windows installation disc. I clicked Repair, Troubleshoot, Advanced Options, then system restore, as I had a backup from a few days ago.

A window popped up:

To use System Restore, you must specify which Windows Installation to restore. Restart this computer, select an Operating System and then select System Restore.

After encountering this error, I tried to refresh and reset my pc. The error message for Refresh PC:

The drive where Windows is installed is locked. Unlock the drive and try again.

So I cancelled, and tried Reset PC. Error message:

Unable to reset your PC. A required drive partition is missing.

I have not made any changes to the hard drives recently, unplugged them or any physical changes to the computer. I have access to CMD from the repair disc.

Can anybody identify the problem, and how I can refresh by unlocking the hard drive, or use System Restore?

Answer

Erasing the system is not what you want!

To make the system boot again, you need to fix the EFI boot stuff. It's related to messages like

The windows boot configuration data file does not contain a valid OS entry
The drive where Windows is installed is locked. Unlock the drive and try again.

Follow these steps - see this blog

1. 
   

   Use a Windows DVD (or USB Stick) to open a repair command prompt.

   
   

   Troubleshoot -> Advanced Options -> Command Prompt

   
   


2. 
   

   Execute these steps - do not enter the comments. But adjust the numbers and the Windows path to match your configuration.

   
   

   // start the disk partition tool
   diskpart    
   // if you have more disks find the correct disk and use its number
   sel disk 0
   // if you have more disks find the correct disk and use its number
   list vol
   // the drive where EFI is on is usually the first FAT32 volume - here 2
   sel vol 2
   // make that volume accessible
   assign letter=z:
   // leave the partition tool
   exit  
   // navigate to the EFI stuff
   z: 
   cd z:\EFI\Microsoft\Boot\
   // fix the boot record
   bootrec /fixboot
   // restore the boot menu - adjust the path to match your windows location
   bcdboot c:\Windows /s z:
   

This is what worked for me.