Hello Spandan Chakrabarty

According to me, it is always better to take a course as your future in which you are interested. If you are not interested in Mechanical but is interested in Aerospace, then apply for Aerospace if you are not fetting it in that college. Search for other colleges. But do the necessary as soon as possible, as you are a 2 year repeater. Also if you have no other potion for college, then go for Mechanical. 

Hope it helps you.