Hello Prachi, 

If you wish to improve on your reading and comprehension part of English then I would suggest you to go through Oxford's Grammar books and the mobile app as well. I would also suggest you to read English Novels, start from Khalid Hosain and then add a level till you reach Shakespeare.

However, if you wish to study it for TOEFL or IELTS,  you can go through apps like Duolingo, Memrise, Babbel and listen to Podcasts in English and watch YouTube English Tutorials.

I hope this was helpful.