He rolls his biological eye.  "No, I don't know anyone who has a magic mirror."

Where's your ballroom?

"The night shift is beneath me," he mutters.  "Floor three."

And the stairs?

"Around the perimeter."

Can she find them on that information?

Yep, they're pretty ostentatious actually, once there's nothing blocking them.  Nice views of both the interior here - balconies overlooking a high-ceilinged central area - and of the lit-up city outside the almost-uninterrupted windows.

(The librarian was thinking of the floor they were on as the zeroth floor instead of the first, so it's not surprising when she goes up two flights and doesn't spot any crystal balls.  ...But there also aren't on the next one up.  Only unfamiliar metal and glass objects, more cuboid than spherical.)

Continuing on the theme of everything looking weird!

They also don't respond to gazing, though.

She goes back down. Guy still unoccupied?

He's on a cuboid of his own, but not with another patron.

I can't figure out how to work the kind of crystal you have here.

"We have computer literacy classes eight times a week."  He waves to a big calendar posted on the tall part of his desk.

...do you remember how I said I was not sure I was on the correct plane? Do you, uh, know what that means.

He sighs.  "Yes.  I know what dimensions are.  They don't work in such a way that you can be from 'another one'.  Everyone anyone on Earth has ever met has been from the same set of three spatial dimensions and one time one."  ...He reconsiders.  "Some computers think in higher dimensions.  But you're not one of them."

That's as may be but I'm not from 'Earth'.

"Anyone from space, either."

Sir, I think I have had a serious magical accident and I am not in the correct plane, and if that sounds to you like the kind of thing that can’t happen here that makes this sound less like where I’m from, not more. I’m not playing a prank, I’m trying to figure out if I can get home if the university cheaps out on retrieval.

"...If you need help getting off drugs, I can direct you to a clinic.  If you want psych assistance I can look up a hotline."

Well, I guess if the psych hotline takes interns who haven't gotten through very many subtle arts classes yet that could be an answer to where my next meal is coming from even though that isn't strictly speaking what I asked.

"I answered what you asked.  Slurry's not good enough for you?"

If we can’t come to an agreement that I’m from another plane can we at least establish common knowledge that you are going to have to explain what things from this one are?

"Have to or what?"

Or fail to impart whatever advice you are trying to produce.

"Oh.  I see."  He produces a tiny cloth from his breast pocket and polishes his mechanical eye a bit.  "Even if you're strung out on some designer strand that makes you forget basic facts about reality and your wallet codes - and that you took it - you can still walk into, literally, any conveni or capsule hotel and pick up a cup of plain Nutrient Slurry, and not starve until you've remembered yourself."

How would I recognize those?

"They're the orange machines with matching cups and spoon straws."