Assuming that, For a wrong reason you have blocked by your friend from WhatsApp account. Now you have no other way to contact with him without WhatApps. But you want to contact with your friend for solving your matter. Here is how you can remove yourself from your friend's blocked list.

Now let's see how you can do this

Open your WhatsApp account and go to Setting option.
Click on Account option. Then click on Delete my account and enter your phone number for deleting your account.
Then Uninstall WhatsApp App from your device.
After complete uninstall then restart your device.
Then again install WhatsApp from Google play store.
Then complete your number verification with previous phone number.

Read more here: http://www.djmedite.com/2016/10/how-to-unblock-yourself-from-whatsapp.html

When the person blocks you the second time nkor? You now repeat the process abi?

Mumu brain