Hard to say, though much of the literature says bright light which can easily be misinterpreted.
The plant need to be up against a window if no sun. Mine are on window sills or are back from a window getting full sun through a matchstick blind through a north window (Southern Hemisphere). They do better with a bit of gentle sunlight, either filtered as described or early morning or late afternoon. Not hot mid-day sun.

Did you repot it?. It is pot-bound? Does the pot have drainage holes?
What is it potted in?

In terms of light, the middle of the living room is practically pitch black to a plant. Still, a Phal will just not grow in two months of those conditions.

The normal process for leaf death is that the bottom leaf will die and a new leaf will grow from the middle, the number of leaves will remain about the same.

Even if you think you are not over watering, I suspect you are. I would not be surprised if most of the roots are not dead.

I had a similar experience with my first orchid... a Phal. It was definitely over-watered, and when I inspected the roots, they were rotted and brown.

I now inspect the roots of orchids BEFORE I purchase, to make certain they're healthy, and that the medium is proper for the plant. Some plants are grown in a soil-type mix covered with bark or sphag as disguise, I've found out. At least, the local garden center here does it this way... not good for the orchid's continued health!

I would check the roots... I agree that it may be too much moisture... and not enough light.

I did not repot it. It is in a clear plastic inner pot, with drainage holes in the bottom; the outside pot is terricotta (but i guess the outside pot does not matter).

I am confused about the roots your were talking about. I am pretty sure what kind and where the roots are for other plants, but I don't know much about orchid. I thought that roots of the orchid is the opposite of other kinds of plants. Those whitish colored fatty strings hanging out of the pot are the roots, right? as opposed to the roots that are at the bottoms of other kinds of plants. They look sort of ok to me. However, the crown part is yellowing, the the yellowing is extending out to the leaves. Is it the over-water syndrome? Is there anyway I can save the plant? Thanks

Hi Chueh,
Yes, those white fatty strings are roots. However, if you're growing in a pot, there are lots of roots underground. These are fat and green and supply moisture and nutrients to the whole plant. You should be able to see them throught the sides of your transparent pot. If they look brown or yellow, you are definitely giving them too much water. Maybe you were never told that orchids in pots are watered differently from other plants? Take the orchid out of the larger pot and water it in a sink or bathtub. You have to pour lots of water in the pot. It should start draining out the bottom almost immediately. Wait until no more water drips out before returning the phal to the larger terracotta pot. If all the roots that you can see in the pot are brown, you should take the orchid out of its pot, cut away the rotten roots and repot the plant in new orchid potting mixture. Hope this helps.
Judy

Oh, good. There are still two green roots among 4 or 5 brown ones in the pot. That means that it still can be saved.... I will drain out as much excess water as possible and repot it. Thank you all

The part that bothers me in your second post is "the crown part is yellowing and extending out to the leaves".

If it is the very center of the plant at the top where the leaves emerge, it sounds like crown rot. If you mean the bottom leaves connected to the center of the plant, then it could just be the normal demise of the leaf.

If the plant is to recover, it needs more light than the center of your room can provide.

Brooke