Antonyms for the phrase "messed with one's head" include "clarified", "enlightened", "reassured", "soothed", and "unruffled". When someone messes with your head, they typically cause confusion, anxiety, or discomfort. Therefore, the opposite effect could be achieved by someone who clarifies a situation, enlightens you with new information, reassures you of your concerns, soothes your worries, or simply helps you remain unruffled and composed. In many cases, it is important to surround oneself with positive influences that uplift, support, and guide towards the right path, as opposed to those who mess with our heads and cause emotional turmoil.