You never solved a problem? You never came up with an idea that improved a situation? Honestly, we don't know you and can't tell you what you have done or how it applies to the job for which you are applying. Don't make too much of this question - just think back to any occassion in which you have solved a problem, improved a situation, or made something better than it was before - I'm sure you have done something applicable. You just need to relax and review your personal experiences for such a situation.
