it´s not about courage, more like I need tips on how to find out her name. I mean, imagine a guy going "Hey, wanna dance with me in prom... person?" or getting your name wrong, it´d be utterly disrespectful.
Asking her friends honestly sounds like the best thing to do. I was gonna suggest to just stalk her social media or something, but that's pretty obvious so I assume you don't have her on anything. You knew her name at one point, right? At least remember what it started with?
I did hear it mentioned a few times, but I was never very active socially, especially not near the opposite gender... but the socially media thing actually seems like a great idea though! Thanks!
And if you don't have/can't find or get her social media, I'd honestly just describe her to people you know at school and hope for the best. Good luck!