New to orchid and petals are withering

[zeroboya]

Hi I was given an orchid last month, and was busy to tend it until last week. During that time, it was being watered everyday, as I know. Now after I took over, I keep my orchid in my office, there is no Window only normal light, from light bulb and since it is office, it is air conditioned.

When I stared to take care of my orchid, the petal has stared to withered a bit, but now it looks very dry and one of the petal came off. It's leaves also started to turn yellow and one of it has a wrinkle on it.

I have attached pictures of my orchid, any help would be appreciated. Thank you.