A photo is no longer as timeless -- or even as "real -- as it once was, thanks to digital technology. Now, photo editing and retouching can fix in-the-moment blemishes, discolorations and askew hairstyles. Sometimes, even meticulous combing can result in photos with messed-up hair. You can use photo editing software to retroactively fix your hairstyle.
Cover the messed-up hair with some other object. You can do this by copying and pasting an item (such as a hat) over the hair. Or, you can finesse it with the image of a tree branch or sign. Of course, avoid using incongruous imagery, and be careful cutting and pasting so the object looks like it belongs.
Take another photo with well-coiffed hair, using the same pose and lighting conditions as the first picture.
Use the hair in the second picture to cover the hair in the first picture. Use the same copy and paste method. Make sure your placement is accurate so the photo looks real.
Apply the blurring feature of your photo software to the hair. Many photo editing programs have a blurring function that will un-focus the area around a designated area of focus. This is often used to great aesthetic effect, and in this case, you can blur your hair while leaving your face intact as a way of obscuring the messiness.