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