![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(128, 8%, 22%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EA%3C/text%3E%3C/svg%3E)
Hi Tomas. I'm Greg, 10 years awarded Windows MVP, specializing in Installation, Performance, Troubleshooting and Activation, here to help you.
So you enabled Ctrl Alt Del as the only way to Login Screen in WIndows (why?) and it's not working?
There are only three ways to turn it off and none of them are easily accessible without signing in. We cannot replace the User account for Command Prompt at boot because the setting applies to all Users. System Restore is about the only thing that seems easy but it might need to be done from bootable media Repair console if it's not working in Winre Repair Mode.
The only thing I can think of that I've done a few times where registry edits are a fix is to extract the registry from bootable media Command Prompt, mount it outside of Windows, do the regedit in this tutorial: https://www.tenforums.com/tutorials/15697-enabl..., then reinstall it to Windows.
To extract, mount and edit the Registry outside of Windows there is a good tutorial here: https://www.winhelponline.com/blog/edit-registr...
To create bootable Windows 10 Installation Media (on another PC if necessary) install Media Creation tool and follow the steps toward the bottom of the download page here in the section "Using the tool to create installation media:"
https://www.microsoft.com/en-US/software-downlo...
Insert media, boot it by powering up PC while pressing the BIOS Boot Menu Key for your PC maker given in this chart: https://www.sysnative.com/forums/hardware-tutor...
If the media won't boot you may need to enter BIOS/UEFI Setup (pressing key given in chart in link above) to turn off Fast Boot or Fast Startup first.
Choose the boot device as a UEFI device if offered, then on second screen choose Repair Your Computer, then Advanced troubleshoot Options, then Command Prompt.
If that doesn't work do this gold standard Windows 10 Clean Install which compiles the best possible Install of Windows which will stay that way as long as you stick with the tools and methods given, has zero reported problems, and is better than any amount of money could buy: http://answers.microsoft.com/en-us/windows/wiki.... Read over it first, take notes, ask back any questions so you're prepared.
You will get and keep the best possible install to the exact extent you stick with the steps, tools and methods in the linked tutorial. It's a great learning experience that will make you the master of your PC because you will learn everything that works best and how to apply it with your own hands.
I hope this helps. Feel free to ask back any questions and let me know how it goes. I will keep working with you until it's resolved.
________________________________________________________
Standard Disclaimer: There are links to non-Microsoft websites. The pages appear to be providing accurate, safe information. Watch out for ads on the sites that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the sites before you decide to download and install it.