I have had this happen to me "at least" once
At the point your plant is looking, I usually give up...I'm being honest.
I evaluate the effort I'm going to have to put into it for the root growth and then get it to flower again and whew!
In the past when my attitude was better, I tried the sphag in a bag and got it to work once. I did it a bit differently with a big old tupperware bin, wet sphag in the bottom and a dash of physan 20 on it. Set the rootless and spikeless orchid on a piece of saran wrap over the moss and closed her up with saran wrap (not the lid).
I tried it with three different plants and it worked for one. That plant grew some decent roots and two small leaves over about a year and then faded.
It is a very discouraging thing when one goes. But don't lose the lesson for the future. I have seen repotme recommended multiple times for their products and I use them with good satisfaction.
Good luck!