CCleaner corrupted my Windows 10 files

Hi Kayla. I'm Greg, an installation specialist and 8 year Windows MVP, here to help you.

CCleaner is not an antivirus. It's a cleaner that gets rid of temporary and other files that aren't needed. It also isn't really needed in Windows 10 which has it's own built-in cleaning and maintenance. All you need in Windows 10 is a good solid install and then to be careful at what you install on it. The built-in Defender anti-virus should be sufficient then to keep you protected.

Go over this checklist to make sure the install is set up correctly, optimized for best performance, and any needed repairs get done: http://answers.microsoft.com/en-us/windows/wiki...

Start with Step 4 to turn off Startup freeloaders which can conflict and cause issues, then Step 7 to check for infection the most thorough way, then step 10 to check for damaged System Files. Then continue with the other steps to go over your install most thoroughly.

If nothing else helps then run a Repair Install by installing the Media Creation Tool and choosing from it to Upgrade Now. This solves many problems and will also bring it up to the latest version which you need anyway and by the most stable method. http://windows.microsoft.com/en-us/windows-10/m...

But remember that Factory or Upgrade installs are inferior installs which most enthusiasts won't even run because they'd expect endless issues. Consider now or later doing the Clean Install in this link which compiles the best possible install that will stay that way as long as you stick with the tools and methods given: http://answers.microsoft.com/en-us/windows/wiki...

There is also an automated Refresh that reinstalls WIndows while shedding corrupting factory bloatware, saves your files, but doesn't clear the drive to get it cleanest: https://www.howtogeek.com/265054/how-to-easily-...

I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.

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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.

When you upgraded from a previous version of Windows or receive a new computer preinstalled with Windows 10, what happened is the hardware (your PC) will get a digital entitlement, where a unique signature of the computer will be stored on Microsoft Activation Servers. The Windows 7 or Windows 8 genuine license you were previously running will be exchanged for a diagnostics key.

Anytime you need to reinstall Windows 10 on that machine, just proceed to reinstall Windows 10. It will automatically reactivate. You will prompted to enter a product key a couple times through the installation, click I don't have a key and Do this later.

There is no need to know or get a new key, but if you have issues with Digital Licensing or the Activation Troubleshooter, you can utilize an existing Windows 7 or Windows 8/8.1 product key you already own to reactivate if necessary. or use the reset function in Windows 10.

Go to a working computer, download, create a bootable copy, then perform a clean install.

	Step 1: How to download official Windows 10 ISO files 

	[http://answers.microsoft.com/en-us/windows/wiki...](http://answers.microsoft.com/en-us/windows/wiki/windows_10-windows_install/how-to-download-official-windows-10-iso-files/35cde7ec-5b6f-481c-a02d-dadf465df326)



	Step 2: How to: Perform a clean install of Windows 10

	[http://answers.microsoft.com/en-us/insider/wiki...](http://answers.microsoft.com/en-us/insider/wiki/insider_wintp-insider_install/how-to-do-a-clean-install-of-windows-10/aef0ae63-2117-41ee-a8ea-4a3181625b08)

Review the following guide for instructions and details about configuring your BIOS or UEFI boot settings for DVD, CD, USB or SD Card.

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BIOS/UEFI Setup Guide: Boot from a CD, DVD, USB Drive or SD Card

https://www.groovypost.com/howto/bios-uefi-setu...

Once your computer is set to boot from the DVD, you should see this option. If you are installing from a retail Windows 10 USB thumb drive, you will be asked to select either 32 or 64 bit Windows 10. Learn more here https://www.groovypost.com/howto/choose-windows...

The Windows logo will appear on screen, this might be here for a while, as long as you see the animating dots, everything should be ok.

Select your Language, Time and Keyboard method then click Next.

Click Install now

Windows 10 setup will prompt you for a product key during installation a couple times. If you originally upgraded from Windows 7 or Windows 8/8.1 click the option 'I don't have a key' and 'Do this later' . If you have a Windows 10 product key, you can proceed to enter it.

Setup will also prompt you to select the edition you have a license for - Home or Pro. Please make sure you choose the right edition. If you choose the wrong edition, your only option will be to perform a clean install again.

The copy of Windows 10 you download and upgrade from will correspond with the edition of Windows you have installed, if it does not, this is why you might be experiencing problems activating:

Windows 7 Starter, Home Basic, Home Premium, Windows 8.0 Core, Windows 8.1 Core should install Windows 10 Home 



Windows 7 Professional, Windows 7 Ultimate, Windows 8.0 Pro, Windows 8.1 Pro should install Windows 10 Pro

Wait while setup prepares to copy files

Accept the license terms then click Next

Click Custom: Install Windows only (advanced)

NOTE: Sometimes Windows 10 setup can become confused if it see's a thumb drive. You might get a driver missing error or something to that effect. If you do, restart setup, but this time, when you arrive at the following screen, disconnect your thumb drive then go through Custom options. When setup is ready copy files, it will prompt you to reconnect the installation source (your USB).

Select the drive then click New

NOTE: If you have multiple partitions listed, select each one (starting at the bottom), then click delete until there is only a single (one) unallocated drive displayed in the window.

Select the unallocated drive listed, click New, click Apply then OK

This will split the drive into multiple partitions, select the Primary partition then click Next.

NOTE: The System Reserved partition is where recovery files are kept for diagnostics and repairing damaged Windows 10 files; or even reinstall Windows 10.

Wait while Windows installs

When this phase of setup is complete, Windows will automatically restart then reboot into setup again.

Windows is detecting and installing your hardware. After this is complete, Windows will restart one last time.

Out of Box Experience

The Out of Box Experience page is where you get to configure detailed settings in Windows, which includes creating a user account, configure privacy, sync PC settings and install modern applications.

Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.

Sorry to hear this. I would never use any program to do any cleaning. They can corrupt your registry and remove your files and corrupt your system.

I would use system restore and restore your PC back to before you did this.