I installed a 24 foot round above ground pool two summers ago. This will be the 3rd summer. I just noticed that one area of the pool is settling. We had to do some leveling before the pool was installed. The contractor dug in on the high side and compacted sand on the lower side. He compacted it with a machine and said it would be fine. Can I somehow bring it back to level without completely removing it and starting over?

A problem with the sand compaction should have shown up before now. Depending on your location, possibly frost heave played a role as soil doesn't always return to its original elevation after deep freezes. Or heavy rains or other underground conditions may have saturated the soil under the pool.
I know little about above ground pools, more about compaction, soil moisture content etc. to be honest. But a foundations contractor or consultant may have some ideas. That will get expensive fast, of course.
My experience is in road construction. When we have an area of subgrade which "pumps" or distorts under loads, we want to be able to excavate a few feet down and see what's there.
Sometimes it's an underground spring, wet clay, bad drainage or even trash from previous use of a property. Once again, I don't know much about pools, but you have to compare the cost of some specialized operation (jacking etc) with the cost of draining the pool, excavating the suspected area and placing underdrain and/or a high quality backfill.