Ways to find messages from blocked contact info
Text messages that are blocked are not saved. So you cannot go in to see old text messages.
If you have a MacBook (I have MacBook Air), you can easily tell if someone has blocked you. With the new iMessage service every message appears as "delivered" (blocked or unblocked), however if your MacBook Air is synced with your iPhone, you will not see a delivered notification on the very same message your iPhone is showing as "delivered".