You won't be able to tell if you've been blocked by someone on Kik. When you've been blocked, you'll still be able to send messages to that person and you'll see a D beside your messages to them. They won't receive your messages though, so the D won't change to an R.
Can I get my Kik back?
You can reactivate your account by signing back in. If you've forgotten your password, you can always reset it, as long as you have access to the email that's registered to your account. To temporarily deactivate your account, you must have access to the email registered to your Kik.
How do you delete a Kik message?
On Kik, you can delete individual messages or entire chats. Individual Messages: Pressing and hold the message you'd like to delete and tap Delete. Deleting a message in your chat won't delete it from your friend's chat since all messages a stored locally on each device.