Q.Best way to save an uprooted hardwood tree
18′ tree transplanted 6 months ago and doing well. Tree leaned from the beginning – did not appear when planted to go in to the hole well. Staked, and restaked in effort to prevent leaning. Strong winds uprooted the tree. It was replanted. Now leaves are turning yellow. From beginning of transplanting, it has been watered every 5-7 days, fertilized about every 6 weeks.

Certified GKH Gardening Expert
After being uprooted, you need to treat it like a newly planted tree. It is suffering from transplant shock at this point in time. This article will explain how to water a newly planted tree:
https://www.gardeningknowhow.com/ornamental/trees/tgen/watering-newly-planted-tree.htm
Start from the beginning on this regimen. Also, give the tree some bonemeal or other phosphorous rich fertilizer to help with root development.