The Color Disappeared on your iPhone and How to Fix It!
The iPhone has so many settings that are great, but sometimes something goes awry and you have no idea how you caused it or how to even fix the problem. Losing the color on your iPhone when it goes to grayscale screen is actually a really easy fix to get it back.
Solution #1 (Feeling Lucky?): First, try triple-clicking the home button (push it three times very fast). For some of you, this will fix the issue right away. This happens because you have “Grayscale chosen as an Accessibility shortcut.
Solution #2: Watch the Video. Converting your iPhone to Grayscale may improve battery life.
Let us know if this worked in the comments below.