"You aren't ok?"
Translation:¿No estás bien?
Not exactly. Saying "No eres bien?" would mean "Are you not a good person?" This goes into ser v. estar, which you can get a detailed description at this site or this rap song, but in the quickest way I can put it, estar means an action or attribute is temporary (Estoy cansado -> I'm tired) while ser means an action or attribute is permanent (Soy alto -> I'm tall).
However some adjectives will change meaning based on whether it's used with ser v. estar. Some, like bien and mal, follow the guideline of permanent v. temporary. Others are less intuitive. For example:
Ser listo = To be smart
Estar listo = To be ready
For a more detailed list of these adjectives, check out this site.
Hope this helps!
I tried 2 times to answer this question. The first attempt: tu no está bien. (was marked wrong.) The second attempt: tu no estás bien. (was marked correct.) Aside from any formality issues, I am not sure why it was marked wrong the first time around. Can anyone shed some light on this.