phalanopsis leaves turned limp and grey
 

hello every one ,about 10 days now my phalanopsis leaves start to turn limp and grey as you can see on the attached pic
how can i save this orchid

Are you giving it direct sun/strong indirect light?

The medium looks quite dry; probably some combination of light and lack of water has caused cell death (mesophyll collapse?).

no, just forget it once for few hours under direct light

The front leaf looks like it might have been sunburned. Sometimes the damage takes a few days to appear. Cold can have the same effect. But since it seems to mostly be that one leaf, I do strongly suspect that it got a bit cooked.

Put it under shade. It doesn't need too much light.
And don't wait for the medium to get dry. Considering the pot size, try for a start to water it once/week (that's what I do to mine under a low humidity, i.e., 30% winter and 15% in summer).