if the wrong button combo happens to be
Left ALt + Left Shift + Print screen then you sure press random keys as I hardly ever press print screen. The combo mentioned will turn on High Contrast mode. THis shows how to turn it off -
https://www.isunshare.com/windows-10/disable-high-contrast-keyboard-shortcut-in-windows-10.html
is it high contrast Mode or just Dark mode?
Dark mode just makes the default windows 10 applications (Like file explorer) show dark backgrounds
High Contrast changes the desktop and the taskbar seems bigger, and you have a choice of colours, there is more than black, think there is a white one too.
See if this helps with the USB thing -
In Visa or Windows 7 there is a feature that allows a...