What to do with students who are not at all interested in learning ?

Firstly you need to understand why they are not interested? Do they not think what is being taught is relevant to them? Are they bored with the teaching style/method? Are they not understanding the course content?

Sometimes we need to look to ourselves as it is not the learner who is not interested, it is us who is not making the learning interesting for them. We need to adapt how we teach in order to capture the interest of all our learners.