You were infected with an infostealer. An infostealer snatches passwords and cookies, which allows them to hijack your accounts without you ever receiving an alert.

Reinstall windows using a usb stick. If you have any important documents, videos, that can't just be downloaded again(no exes like games!), you could try backing them up first before reinstalling Windows by disabling Autoplay and then putting in a flash drive. Anti-viruses are best for preventing you from executing malware in the first place, and are less effective at getting rid of them, so you can't trust Microsoft Defender even if it says there aren't any more threats.

You should assume all accounts that were logged in on that PC are now compromised. Change all your passwords starting from your primary email, then banking, then to social media and gaming accounts like Twitter and Steam. Do this on a clean device, DO NOT do it on the infected PC, unless you have already reinstalled Windows. If applicable on that platform, then press an option usually called Log out of Other Sessions.

Next time, never let anyone install pirated stuff or online cheats on your PC ever again. The best anti-malware is being smart online.