the difference between haven't seen you and didn's see you ????
tell me the difference between
1. I haven't seen you for a long time ,where have you been ?
and
2. I didn't see you for a long time, Where did you go ?
and
3. I haven't seen you for a long time . Where did you go ?

Which is right ? and what's the difference?

Question

the difference between haven't seen you and didn's see you ????
 tell me the difference between 
1. I haven't seen you for a long time ,where have you been ? 
and 
2. I didn't see you for a long time, Where did you go ? 
and 
3. I haven't seen you for a long time . Where did you go ? 


Which is right ? and what's the difference?

Answer

Grammatically the FIRST one is correct.
LONG TIME specifies a period of time and therefore it will come with HAS, HAVE or HAD.
DID/DIDN'T is for something that happens at a given time. Therefore, you cannot say I DIDN'T SEE YOU FOR A LONG TIME. You can say I DIDN'T SEE YOU WHEN I LOOKED FOR YOU (i.e. at the time I wanted to see you). 
You can say I WAS AT TRAIN STATION AT 10AM (a given moment) or I HAVE BEEN AT TRAIN STATION FROM 8AM TILL 10AM FOR 2 HOURS (i.e. a period of time).

Hope this helps.

Answer

the first is right, because "have been" -it's a result and It's Present Perfect tense
did-it's Past  Simple Tense, the action happend in the past

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!