I...that's a pretty big ****-up. I mean, all this shit is labelled somewhat well for anyone who's done it a few times. Following a guide as a first timer, even moreso. A USB external drive can be formatted while you're already booted and in Windows, making those labels even easier to see as you can go back to basics and see what drive shows up when you unplug and plug in. No, you shouldn't be near her computer anymore, lol.

If you didn't know what the hell you were doing, why were you touching it in the first place?

You shouldn't be allowed on any computers anymore. Abacuses can be fun.

On the one hand, yeah, she's right. On the other hand, I'm the computer person in the household, and I've come within half a second of doing that once or twice. It is disturbingly easy to click the wrong drive or partition in some operating systems, especially in the middle of something complex, when you can't spare the attention for every single time the computer asks you to confirm. "Do you really want to overwrite this file?" "Yes, this is the newer version of the same file. Stop bugging me." "Do you really want to remove this partition?" "Yes, that's exactly what I have to do to fix it. Oh, wait. Wrong partition. Fuuuuuuuu-"

That's literally so hard to do, you really shouldn't be deleting anything on a computer like at all.