If you're on someones Instagram profile and you get the message 'No posts yet' it means that person has blocked you. This means you will not be able to view any of their pictures or interactions on their own page.
In the case of being blocked you will not be notified and this message is the only way to know for sure, unless they have actually deleted all their pictures.
If you're interested in how to block or unblock a user this site gives a step by step walkthrough: http://www.wikihow.com/Block-and-Unblock-Users-on-Instagram
If you want to get around being unblocked you can always create a new account and view the user through that, or alternatively it may be possible to search the users name on the Instagram search and find pictures tagged with their name.
It is important to consider why you may have been blocked, whether it's because of privacy reasons or if you are doing/have done something to upset the user like posting hateful comments or spam. If you want to be unblocked the best way is to make amends with the user and this can be done through hashtagging their name in a comment on a different picture, which they should be able to read.
