It does sound as if you damaged the roots when you dug it out from its former situation. Ginkgo are slow growing, so unless you bought a mature plant initially, reaching 7 feet will have taken some years, so the root spread would likely have been both deep and wide.
There is nothing you can do other than keep it well watered - it will take time for it to put out fine roots to seek out water, so you must provide it probably daily unless its raining very hard, a few gallons at a time, in hopes it survives, and likely right up to Fall (not sure when that is where you are). Were it another plant, I'd suggest reducing the topgrowth by half to give it less work to do, but as its a Ginkgo and they take so long to grow, you might not want to do this. You might find you need to prune out some parts which have died back anyway though, but wait till next year if you're not going to reduce it now.