Hey Vinay.

If a candidate has not qualified for the JEE Advanced, then he cannot go for the counselling of NITs and other colleges. There are other private colleges which accept the JEE Main score and can be applied for if you haven't cleared the JEE Main. But there are some NITs in the north east which have vacant seats until the starting of the session. They then invite application for students who want to take admissions there. Then you can try and get admission in those NITs.

Hope this helps. All the best.