At the risk of being a smarta$$, I'll be the first to answer.

You have heard of topsoil, right?

Is there more to this problem than meets the eye?

Are the ruts there because someone drove over your lawn, or the lawn is constantly damp or wet?

Are the potholes more like sink holes?

Am I missing something hear?

 

Pretty straight forward as grass4gas mentioned. Topsoil until fairly level (might need to tamp it down slightly) followed by sod or grass seed of your choice.

 

If the turf is healthy and you don't want to kill it by smothering it with top soil, you can cut it out and then fill and put it back, but be sure to accomodate for the thickness of the sod you're putting back. If it's really bad, you might have to re-grade the whole lawn. It amazes me that on some of the new lawns around me, they just backblade with a dozer and seed over it without raking or any other type of final grading.