A long time ago (I cannot find it anymore, may have been deleted) I read a "tale from tech support" where a user called tech support and complained "my operating system is missing". Retelling from memory:

Tech support person tried to walk the user through various steps until the user said "ok, let me just close these documents…"

"Wait, you have open documents? Your operating system is not missing."

"What? No, it is."

"If your operating system were missing, you wouldn't be able to do anything with your computer, you wouldn't have open documents. If you can do that, you definitely have some operating system. What version of Windows is the computer running?"

"Windows 7."

"There you have it, that's your operating system."

"That's Windows, not operating system."