Hello muskan

Usually these courses ( m.phil and phd) doesn't have any age related criteria .I said usually because it might vary for some institutes .So yes you can do these courses even after taking 3 gap years .But you must satisfy the other eligibility criteria as well and also be able to crack the respective entrance exams of your course .Checkout the eligibility criteria for m.phil

https://www.google.com/amp/s/www.careers360.com/courses/m-phil-master-of-philosophy/amp