I am from village.i want to be fashion designer but..in Mumbai..it not possible.here in kolkata medical college situated.so..........I think ...what to do...

Look always go according to your wish, what you want to do & what you can.. I would suggest you that..

Fashion designing k barein Mein bad Mein atein hein, 1st I would clear your views on medical as you said 'medical colleges in Kolkata'..
Look, as you are belonging to West Bengal, so you only exam, NEET to get medical. & I think you should know, NEET has it's level. It's all India based exam & it's really very hard. So, jaise tum bol rahe or soch rahe ho medical k barein Mein, vaisa bilkul nehein hein. & as you mentioned, you are from village, so I think you should face lack of money & proper guidance of education. & if you want to get Kolkata government medical colleges, so you need to rank at least 10,000 in NEET. So, it's quite tough but not impossible.

But you are really passionate about medical & if you have that kind of quality to get Kolkata government medical colleges then definitely go with medical, because MBBS is ever green.

Otherwise time waste.

Now, I come to the point of your interest, Fashion Designing.

Look, first you should tell me, fashion design k liye Mumbai Jana parega Yeh kisne bataya apko pehle aap Yeh batao?!!

Jaisa Medical has it's own entrance, vaisa fashion design has it's own entrance. Many entrances.

So you should prepare for that, & conquer your dreams.
Because I believe, always follow your dreams they will definitely find their way..

Please check out the link below for fashion designing entrances- https://www.shiksha.com/design/fashion-design/articles/top-design-entrance-exams-2017-conducted-in-india-blogId-11334

I would recommend you to study for NIFT, it is national based exam, so it has it's own value.

Good luck!

Please check the link below for NIFT Kolkata, as your seeking to study in Kolkata..

It is ranked 4 fashion designing institute in India.

Https://www.shiksha.com/college/national-institute-of-fashion-technology-kolkata-salt-lake-city-27351