In addition to the above, i like to mention that he can write around 50 words (4-5 lr words). But not sentences. I don't know how and where to start. Pls guide me.
Now, this is very difficult to suggest online, especially when I am sensing other developmental problems from your post. There are various factors to consider when it comes to reading (speech, sequential skills, comprehension skills, child's reading level and much more). Please check this http://www.learningstations.blogspot.in/
If you are in Bangalore, we can meet up once.
At the most general level, good books to start reading (without assistance) are the level 1 books of "I can read" series(scholastic, random house etc). You may read illustrated books by Eric Carle, Julia Donaldson to your child.