There are two things you're talking about and may or may not be at all related.
If you can't initiate the downswing by unwinding from ground up, you may have slid to the back foot and are stuck with too much weight on the back foot. Or, you may have let your front knee collapse inward during the backswing and it's stuck. Practice keeping the front knee on top of the front foot with some short practice drills to see if it helps. If not I need to see what's up. There are many different reasons, things that can "break down" during the backswing. "Distance" is not just one thing. There are reasons and combinations of reasons why there can be a lack of distance. We have discussed it many times here in the forums if you search, you'll find those discussions. The most important thing is learning to freely unwind and accelerate to the finish first. Then work at making it go farther.
Move Less ... Get Good! DUPLESSISGOLF