These questions surely look like questions from a course or exam. And these forums are not for making anyone elses homework. You'll learn more if you do that yourself.
So I don't expect answers will come here.
I am looking for someone who can help me finding an answer for these 2 questions.
1: The steps that you would take if two OSPF routers do not share routes even though you can ping the other router. What things would you try in order to find the problem?
2. Compare and contrast HDLC and PPP. On what OSI layer do these protocols operate? When might you use one versus the other?