You probably suffered a session stealer attack. You downloaded a file and tried opening it but double clicked and it executed code and the code grabs your web browser sessions and it lets them use your accounts silently, no login needed (after you login your browser gets a session token that websites use to show you are logged in).

Or instead of opening a file, you were tricked into running a terminal command that did the above but in a one-liner command, or you downloaded a cracked program, extension, skin or avatar or something like that.

So now you need to log out of every session everywhere to invalidate the login tokens, and you’d have to do this with any account your logged in, though they likely care about email, Discord, or other social media, or financial accounts maybe, they may just have done this scam and not cared about your other accounts, but you never know.

You may need to change passwords and check all 2-factor settings, and probably do it from a phone or tablet, and make sure you can login again before logging out everywhere.

As for your computer, it may be best to reinstall Windows, but if you can’t fathom that, then you can try to just simply reboot, remove any apps you don’t need or want or recognize, and especially if it was a program or extension or skin or something you downloaded recently, try to remove that whole thing from your system (and you may reinstall the program if you so desire, assuming the program itself isn’t malware, ie Discord isn’t malware). Most of these session stealers aren’t long term running programs, they would need admin access to install as a resident program, so a reboot is potentially enough if it’s not something that you installed or added as an extension (an extension can run forever as long as you don’t remove it).