Q.My Phalaenopsis was sick when my son purchased it. All the leaves fell off; the roots looks good and it’s still in bloom. How can I save
my Orchid? Should I place it in water ??? help

It may have had some improper watering and caused some rot on the plant.
As long as the roots look good and the actual flower is intact; it will likely survive.
I'm listing some care articles for you to optimize its chances.
https://www.gardeningknowhow.com/ornamental/flowers/orchids/indoor-orchid-care.htm
https://www.gardeningknowhow.com/ornamental/flowers/orchids/beginner-orchid-growing.htm
https://www.gardeningknowhow.com/ornamental/flowers/orchids/phalaenopsis-orchids-post-bloom.htm