Hello Dhananjay
To become a professor in English first you have to do masters in English from a recognized university. After which you can apply for NET exams. There are also n no of private college and university in India where they directly appoints professor by passing NET exam. I suggest look for those options
50% is not bad but it is true you have to work hard.

All the best for your future.

Dear student
Don't worry you have secure 50 percent mark in graduation first you go to master degree and then P.H.D you try to secure good mark in master degree and PhD definitely you become a future professor job .
After you pass PhD you join any college assistant professor and then few year you become a professor.
I hope you understand.