Hello Sarah, There are many reasons why the petals would have fallen
off, once finished they will drop, the climate may have knocked them if
it was warm to cold, any small bumps will also dislodge the delicate
petals, i keep mine in a sheltered area with as much heat as possible,
with minimal watering most of the year, winter less watering. One of my
orchids is growing great after repotting, in their case the bulbs are
thrown into an old terracotta pot with loose pumice growing medium,
very little. they are thriving so i left them. I remove dead stalks
once dead/ dry, cutting as close to the bulbs as possible taking care
not to snip the bulb. I repotted some of the bulbs like you mentioned
you had that looked dry, try potting them and a good watering in. Keep
them somewhere warm.good luck.
Check out some of my orchids in my blog.
www.nzlandscapes.blogspot.com
www.nzlandscapes.com