Victim of Windows 8 startup password lockout

We are stuck on this "startup password" screen (identical to the one posted on this thread) after receiving one of those "microsoft calls" that threatened to shut down computer if the "discovered" malware wasn't removed for a mere $350. Wife realized it was a scam too late after giving access to computer. Now we can't get anywhere on the computer other than the f2 f10 options. Have tried the f10 reboots using recover disc but always comes back to the "startup password" w/ no known password to work.

Are we dead in the water or is there a workaround for this?

Thanx in advance.

What model of computer ? Try F8 and F12.

I am assuming that you have access to another computer to make this post.
If you wish. You can try:

1. Download the Macrium Rescue disk: https://drive.google.com/open?id=0BxgxYnZOV7L7ZmRGWjRaNnBsWWc&authuser=0
2. Use: Rufus - Create bootable USB to create a bootable CD/USB
3. Boot up the troubled PC using the CD/USB, you'll see the screen similar in step 4.
4. On the bottom left, you'll see a command prompt icon as shown below, ignore the other screens:
   
5. Click on the command prompt icon to open it then type:
   cd \windows\system32\config\regback
   xcopy c:\windows\system32\config\regback c:\windows\system32\config
6. The above will restore the registry database from the backup folder.
7. Reboot the PC to see if it fixes the problem.

Good luck!!!