At a point of time I was also not able to understand recursion. Then I referred some books. That is programming in c by reema thereja. In that book detailed concepts are given in a lucid manner and solved examples are given. From that you can understand the concepts. Then after solve the problems in the exercise. That would solve your query related to this topic. You can also refer sourabh shukla sir lectures in youtube if don't understand after all this.