My guess is shock if the root ball was handled to much. They will probably recover. If you have them in sun that is another reason they will wilt. Most all Impatiens want shade even those that are said to do well in sun. The exception are the Sunpatiens which will take direct sun.

One thing I have done is that when I see the leaves are so wilted and the stem so limp the impatiens is not coming back I take cuttings and put them in water. They get nice and firm pretty fast. Roots will soon appear. If the plants are not perking up yet, that would be worth a try. Good luck.