We use the Sino-Korean numbers when saying years, minutes, seconds or counting money, so it should be "천 구백 구십 년 일월 이십일" for 1990년 1월 20일, and unfortunately no other ways.^^ The second one you commented on your post would be "잊을 수(가) 없어요", here "가" is put to emphasize the sentence. \^o^/

Sometimes it can be read as "일"천 구백 구십 년 ~~~ to emphasize its numbers. But it's not common way.

aku ingin sekali bisa berbahasa korea. Ada yang bisa membantu? ☞ 난 한국어를 배우고 싶어. 도와줄 사람있어? (quite informal), 전 한국어를 배우고 싶어요. 누구 도와주실분 계신가요?(formal and polite) ^^ ...haha six months ago.

안뇨. 난 천구백팔십칠년 오월 십일일.^-^ Actually. "awak" is much used at Sumatera Island (one of Indonesia's island of course.kekekek) You = Anda, Kamu, kau, elo (Jakarta dialect)..^-^ I'm pretty sure you've already known it.

1990 년 1월 20일 ☜ hari jadi awak? ^^