I have been create a project and suddenly my first person character wont move in the gameplay state?
Well, this could be just about anything. I guess to start, you could bind a random keyboard key to a print string just to check that the character is receiving input.
You could also put a print string attached to the movement bind itself (print the axis) to see if that is receiving input when you move.
If everything is receiving input, is there any chance you have changed or altered the movement nodes since you last played?