Are you able to get into Safe Mode to run the program again to use the Registry Restore option ?
Are you using Win 8 or Win 8.1 - 32 or 64 bit and is this machine a purpose or OEM (branded) build.
You should be able to create a bootable disk from
https://www.microsoft.com/en-gb/software-download/windows8 but I believe you need to download it onto a machine with the same architecture as the affected machine so that you get the correct 32 or 64 bit version.
https://www.microsoft.com/en-gb/software-download/windows8You may need to change the boot order to boot with the install disk.
If you are unable to restore the machine back then press and hold F2 as you switch the machine on and hopefully that will get you into the BIOS to change the Boot order.
This article may help you from there -
https://grok.lsu.edu/article.aspx?articleid=17293However, if your machine uses an UEFI BIOS then the steps will be different.
This article is from Dell but may be similar in general for your computer if another brand.
http://www.dell.com/support/article/uk/en/ukbsdt1/sln142679/how-to-enable-boot-from-dvd-option-with-uefi-boot-mode-enabled--windows-8--81--10-?lang=enIf you are able to boot up with the install disk, proceed as for a clean install but when you get to the install screen, click on Repair your computer which is usually on the bottom left of the screen and navigate to the recovery options.
Selecting Command Prompt you can run a chkdsk /f but first you will need to enter
bcdedit |find "osdevice" to see which partition it sees the volume in as it isn't always c:
For clarity, that is a Pipe symbol before
find and is the uppercase of \
Enter chkdsk x: /f where x is your partition letter.
The machine doesn't have to dismount the volume so you will see what it does on screen.
Disregard the error 50 at the end of the report as that just means it can't write the report to a Wininit log in Event Viewer because you aren't booted into Windows.
Enter exit to close the command window.
If the chkdsk reports that it has made repairs then you can see if the machine will boot up normally.
You can also run an offboot sfc /scannow from the cmd prompt to check the system files.
Again using your partition letter instead of the X I'm using, enter -
sfc /scannow /offbootdir=X:\ /offwindir=X:\Windows
Note there is a space before each /
You won't see any % progression as you would when running a sfc /scannow from within Windows but it will be running and takes a bit longer to complete than when run from within Windows.
If you need to run that cmd then let us know what it reports.
From the cmd window you can also access your restore points if unable to from the recovery options.
You can do this by entering
rstrui.exeHopefully these steps will enable you to get back into your machine, but what was the problem you were wanting the repair program to resolve ?