My husband purchased some orchids for me that he found on clearance at Kroger. They needed some serious TLC. I am far from an orchid expert but from everything I had read the first thing you had to do was to repot them and them nurse them slowly back to health. One of the important things to do as to also make sure they get a good feeding of orchid food every 2 weeks or so.
I purchased a bag of Orchid Plus water soluble orchid food to use to feed them. It comes in a resealable 1 pound bag and is recommended by the American Orchid society. It is a 20-14-13 formula plus it also contains other essential minor elements to combat deficiencies that occur with soiless potting mixtures which my orchids are planted in. The directions for use are to use 1 teaspoon of the mix with one gallon of water if you are going to use it as part of every feeding or use 1 tablespoon per gallon and feed every 14-21 days. Since I read that you should feed them every 2 weeks, I went with the stronger mixture and use it every 2-3 weeks.
One of the orchids I had dropped all but 2 of it leaves shortly after I received it and I was sure it had no hope of survival. To my amazement it has been 5 months now an it is currently in the process of adding a third new leaf and just yesterday I noticed that it is sending off a shoot that appears to be a new flower stem. I truly believe the Orchid Plus food is one of the reasons the plant is doing that well today.