How do you define wonder?
I have wondered at the incredible beauty and sometimes human-like behavior of wild horses. I have also wondered at the beauty and depth of color in flowers, of the gorgeous clouds in the sky, etc. Don't you appreciate these types of things?
Maybe if you slowed down and took the time to more closely view the world around you, this wonder could return to you. It might be a matter of taking the time for yourself. I think that is how if works for me, anyway.