Dear Yan,
I am sure there are more qualified experts on here that I am, but I live only a couple of hour north of you (so my condition as similar) and I grow a couple phals., so here are my experiences in a nut shell.
for phals.
1) Moss kills (for most amateurs). Get rid of it. Make sure you get rid of it all. Use tweezers if you have to, to get it from the center of the root mass.
2) Be patient. I suggest you put your phal. into a bark mix. (ex. shultz orchid mixz, should be available at home depot) and water it using the
skewer method. If most of your roots are gone, as it seems, then you might be in for the long haul and it might not be worth the effort. This depends on you.
3) Make sure the pot you are using is the right size. If it is too large, then you will suffocate the existing roots. The pot should be big enough to just accommodate the roots. I often rotate my orchid into it's home, then fill around it. Don't be afraid to down size.
Hopefully this helps a little.
Steve.