I'm trying to learn (refresh, actually) stuff about X and vt* etc.

I was fooling around, and somehow screwed up, hit a black screen, and even the usual Ctrl-Alt-F1/F2/...F7 to get to a Console didn't work anymore at all (no reaction).

First of all, is my understanding correct that Ctrl-Alt-F1/F2/...F7 is a "kernel" functionality? As in, which code traps Ctrl-Alt-F1/F2/...F7 and.. does something about it?

If Ctrl-Alt-F1/F2/...F7 don't work anymore, has the kernel panic'd and you really have to reboot? Or would ssh in from another machine still have worked (I hadn't tried - and don't know how to screw it up again..) Is there another way to get a terminal to kill.. something to re-establish Ctrl-Alt-F1/F2/...F7 (what) ?

This is just for learning - no actual real life problem. Thanks!