Hi romromillys:
What is your computer make/model, do you use CCleaner Free or Professional, and does your Win 10 computer have a discrete graphics card (e.g., NVIDIA GeForce, AMD Radeon, etc.)? Do you make regular backups of your personal data (e.g., your C:\Users<yourusername>\ folder) to an external USB backup drive or cloud service like OneDrive, just in case you need to perform a repair or emergency recovery of your Windows OS and need to restore your personal data if anything goes wrong?
Do you have any third-party software installed on your computer that can be used for an emergency recovery? For example, most Dell computers have software named Dell SupportAssist OS Recovery (also known as Dell SupportAssist Remediation and/or System Repair). I uninstalled that software from my Dell laptop and now use Macrium Reflect Free v8.0 imaging software (unsupported since Jan 2024 but still fully functional) to create emergency recovery media (a bootable USB stick) and the occasional full disk image of my entire hard drive just in case I ever have to perform an emergency system recovery. Note: For future reference, other good free options are reviewed in the June 2023 Tech Republic article Top 5 Free & Reliable Hard Disk Drive Cloning Software.
It’s difficult to tell from your description if your Win 10 computer screen is black because you’ve damaged your Windows operating system and your system won’t boot up, or if you’ve damaged the graphics driver for your display. If you can boot up in Safe Mode with Networking from a blank screen as instructed in the Microsoft support article Windows Startup Settings (which will try to start your system with minimal services and drivers, including a low-resolution graphics driver that comes with your Windows OS) that might indicate a problem with your graphics driver. Note: You can exit Safe Mode with Networking by restarting your computer, but when your system reboots in “normal” mode you will likely see your black screen again.
Do you know if Windows System Restore is enabled on your computer (this feature is normally disabled in Win 10 and Win 11), and have you tried a System Repair from your Windows Recovery Environment as instructed in the MS support article Recovery Options in Windows? Note: Post back before attempting any System Restore or System Repair if you do not have a recent backup of your personal data on an external USB backup drive or cloud service like OneDrive.
This won’t help now, but please read the CCleaner support article Clean the Windows Registry, which includes the following warning:
We recommend examining Registry Cleaner’s fixing options carefully:
This is important if you select parts of the Registry that you want to clean (see screenshot) but are unsure what will happen if you remove them. We’ve made CCleaner’s fixing options (listed beneath Registry Cleaner) in Registry > Registry Cleaner to help reduce potentially harmful results. It’s always safer to leave an entry than to remove it if you’re not 100% sure.
If you have CCleaner Professional and use the Driver Updater tool, also note that CCleaner Driver Updater board at https://community.ccleaner.com/c/ccleaner-for-windows/driver-updater/25 is full of posts from users who damaged their system after allowing CCleaner to update their drivers, with problems ranging from loss of sound from their audio card to being left with an unbootable computer.
Dell Inspiron 15 5584 * 64-bit Win 10 Pro v22H2 build 19045.5131 * Firefox v133.0.0 * Microsoft Defender v4.18.24090.11-1.1.24090.11 * Malwarebytes Premium v5.2.2.154-1.0.5101 * Macrium Reflect Free v8.0.7783 * CCleaner Free Portable v6.30.11385