Why My Character Flying Off Ground?

I have been working on my project for some time as well as having a lot of issues along the way, but that is a different story. Reciently, I have been working on my landscaping, planting plants and trees and setting rocks etc. Now, for some reasion unknown, when I go to test the project using the Standalone Game option, I noticed that my Character now seem to fly straight up off the ground for some distance and then stops. I can run around in the air but unable to get to the ground like he is to be in the first place. Any idea how to solve this? Is there an option in a configuration that may been changed without my recalling which it may been? Any how, here is a screen shot of what is going on. Thanks in advance.