I'm not a phal expert, but you can save that plant.
I would get some powdered rooting hormone (I use Rootone). Trim away all the dead roots, stem below the semi healthy roots and the dead leaves. Get some good sphag and wet it, then wring it out till it is just damp. Dust the bottom of the plant up to the good leaves with the rooting hormone, wrap the plant in the sphag (Not tightly) and place in a plastic pot. Put the plant in a very low light area and mist the sphag every day to keep it moist, not wet. Once the plant has some new roots about 2 inches long pot it in a small bark mix and resume normal watering - for bark I would estimate once a week but you will have to figure out the right schedule based on your environment.
Let us know how it goes.