What can I do for wilting and brown elephant ears
I planted them in my gardens and some of them have wilted and turned brown.
There are many species of elephant ear, with differing needs, so the first thing is to make sure yours has the light specified on the plant tag. The next thing is moisture -- elephant ears require moist soil, but even they can be drowned. Too much moisture and too little moisture can result in brown and wilted plants. This article tells you how to determine the moisture in the soil: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm
Here are a couple of articles with more information on elephant ear plants: https://www.gardeningknowhow.com/ornamental/bulbs/elephant-ear/growing-elephant-ear-plants.htm