This should be simple. It will grow roots again. I think Cyms are the easiest to grow this way.
Of all the orchids I have almost killed
I saved all the cyms by one of the bottom two trusted propagation methods.
First of all...
If you have any cinnamon (without sugar, look at the ingredients) (ask your folks or try the kitchen spice rack) sprinkle a little on the cuts to seal the wounds and stop fungi getting hold.
If no cinnamon just dry out the bulb for few hours so the cuts can seal.
And if you have a little Rooting Hormone sprinkle a little on as well. (If you don't have rooting hormones handy don't worry just get some from your nursery or Big W that has garden supplies later in the week and sprinkle it on and then water).
PS: I don't use Rooting Hormone, it seems to do well anyway. But many people say it helps.
After you have prepared there are two ways I know of one a normal potting then bagging or spag and bag.
method 1..this is what I use for cyms..works well.
Make sure you but the bulb in a nice draining orchid mix in a small pot, water well, put it into a clear plastic bag and seal to keep the humidity up.
method 2
just put the bulb in a clear plastic bag with a little spag and seal. If you don't have spag moss, just use little strips of paper. Remember that both spag or paper should not be dripping wet and it should be HARD to squeeze/drain out excess water. The Spag or paper strip is just there to hold a little moisture. The bag should not have any free water one the bottom of the bag.
Finally after you finished one of the two way above put it into a nice warm position, away from direct sun but bright.
All should be fine.
But remember only water VERY little and there should be NO free floating water in the bag.
I am sure members that are more knowlegeble will say more.