Question regarding problem I am having with facebook...

Hey there. I am having somewhat of a difficulty adding my younger brother on facebook. My younger brother blocked me a while ago, but he has my old account. I made a new account and I tried to add him, but it does not work. I typed his name in the search box, and his profile does not show up. My question is how do you unblock someone you have blocked in the past? Is it possible?
Please help me! Thank you