CCleaner just ruined my computer

[Jayyy]

Hi All,

I just got a new computer -- windows 10 pro.

Everything was running great! Firefox set as default browser.

Then I downloaded and ran CCleaner. I got the free version to try before upgrading. I made the mistake of clicking "Make It Better" after the health check analysis.

Now  "Settings" comes up with an image of the gear symbol in the middle of the screen -- and nothing else. Firefox is suddenly not the default browser anymore. God knows what else CCleaner did to my computer.

How do I quickly UNDO what CCleaner just did to my brand new computer?

[nukecad]

CCleaner does not do that, if it changed defaut browsers and broke Windows settings then everyone would be shouting about it.
(Firefox is my default browser and CCleaner has never changed that).

One thing that might do that is if you accepted a bundled offer and downloaded/installed CCleaner Browser (or Google Chrome) as well as CCleaner itself, so that the new browser has set itself as the default.
What browser is now opening as default for you?

It's easy enough to set the default browser back to Firefox.
https://blog.mozilla.org/firefox/how-to-set-firefox-as-your-default-browser-on-windows/

Of course you need to get to settings to do that, and you say that is not loading properly.
I'm not sure why that should be happening, but as you say this is a new computer then it may have been an automatic Windows update.
Some previous Windows updates have been known to break settings and search in Windows. (I've had it happen once with settings).

The first thing to try there would be a Restart of Windows 10 (Restart not shutdown/reboot) and see if the settings work then.
If it's still not working after a restart then you could try scanning/repairing Windows using dism and/or sfc.
See this article for how to do that: (Myself I'd use sfc first and if that doesn't fix things then I'd try dism).
https://www.windowscentral.com/how-use-dism-command-line-utility-repair-windows-10-image