Manhwa with a girl who dies and is reincarnated in the past

Question

So I've been looking for this manhwa that I have not finished and I can't stop thinking about it. Here's all I can remember: it starts off with this orphan girl who is poor and works at a convenience store. She ends up dying somehow and is reincarnated back to a prior time in history with concubines and stuff. She wakes up seeing this hot guy who seems to be her friend. He has white hair and is wearing blue. She can't read the writing because she is in the past. And later on in the story she ends up being exiled from the place.

Answer 1

This is Ellin's Solhwa.

The last thing Ellin remembers is having to deal with a belligerent customer at her dead-end job. And when she opened her eyes… she’s “Solhwa,” the beautiful fourth concubine to the king of the Xyaran Empire. Between trying to learn the language and eating steak, Ellin’s trying to figure exactly what’s going on. Where is she? How did this happen? And who can she trust: Solhwa’s handsome charismatic childhood friend or the elegant, raven-haired king’s advisor?

The story opens with Ellin working at a convenience store, dealing with an irate customer. Her parents are dead; her mom died of a disease that Ellin inherited, and she dies shortly after. She reincarnates as a concubine, in training to potentially become queen, but doesn't remember anything about her new body and can't read or write.

The first thing she sees when she wakes up is her childhood friend, with silver hair

She does eventually get into trouble due to her perceived closeness to the king's advisor (as mentioned in the synopsis).