Can ear infection be cure with antibiotics? how long does it take to get back to normal?

Yes, usually: The two common types of "ear infections" are external (a.k.a. swimmer's ear) and middle ear infections. Swimmer's ear is best treated with topical antibiotic and steroid ear drops and usually feels better within a few days to a week or so. Middle ear infections are treated with oral antibiotics. Pain improves within 2-3 days but some muffled hearing can last weeks due to fluid under the eardrum.

If from bacteria: While bacteria commonly are the culprits causing an ear infection, the most common cause is actually a viral infection. If it is bacterial, which is more common in infants and small children, antibiotics will indeed cure it. But it can take up to 8-12 weeks to get entirely back to normal. Even after the infection clears, thee can be fluid that persists that will very gradually resolve in that time