Your plant is dehydrated from rotted roots. You need to find a different pot. That pot is too deep and wide making the plant over potted which keeps the medium too wet and rots the roots. That pot is meant as a decrotive container not one to plant the orchid directly in. Also take the moss off the top. If your going by the moss being dry or the surface of the bark being dry you are not letting the plant dry out enough between waterings. Even if the top is dry the inside of the pot might not be. So you are over watering the plant in that pot. Also in that pot which also doesn't breath like a unglazed terra cotta pot the medium stays wet way too long.
Phalaenopsis orchids grow on trees in the wild with their roots exposed to the air all the time. They are not in any medium. We put most orchids in pots so it's easier for us to grow them. The medium is used to keep some moisture and humidity around the roots to try and give them the humid environment they like.
To give this plant a chance you need to get a new pot that just fits the healthy roots. Since it doesn't have many the pot should be small. You want to match the pot to the roots not the top growth. I would also get a bark mix of some kind. Many people like clear plastic pots because you can see the root development and you can see if the roots and medium are wet or dry. Phal roots also photosynthesize if they are exposed to light.
Many people have a hard time knowing when to water and a lot of people kill their first orchid by overwatering. It's worse than letting the plant go dry for a few days. Actually my Phal NoID has gone a week or more completely dry a few times and it's fine. I don't recommend doing that often though!
So a lot of people use a wooden kabob skewer to take the guess work out of watering. Put a skewer in the middle of the pot and keep it there. Make sure you don't stab any roots though. You want it in the middle of the pot with it all the way to the bottom of the medium because that is where it dries out last. Even if the top is dry the little bit of moisture in the middle is enough for the plant. To check when to water, pull it out of the pot. Many people touch it to their cheek and if it is damp or wet it is not time to water. If it is dry then water. If you are not sure if it is dry enough wait one more day and check again. Make sure you put the skewer back in the same place.
Good luck and I hope you can save your plant. I'm sure others will give you some advice too. If you haven't read the Phal Abuse Ends Here thread I recommend it. It is long but it has a lot of great info on Phals. It's in the beginner section and it should be close to the top of the page. If you have anymore questions let us know.