Spring and autumn-flowering cyclamen

They may have been eaten by Slugs or Snails. Some of mine suffered quite badly , but seem to have ignored them noow they are older.

Out of interest what kind of Cyclamen were they?

They were cyclamen coum and hederifolium

Are they planted under deciduous trees, are they having to compete with weeds such as long grass and did you plant them at the correct (very shallow) depth? Sorry to answer your question with more questions!

They are planted under deciduous trees and they could possibly have been planted too deeply and at present the fallen leaves have mounted up a bit round them. The grass isn't long but there may be a bit of competition around the plants so that could be it, I suppose.... Thanks everyone for the help, anyway. I've only just joined and you ARE a kind, friendly bunch!

Certainly niether of these species like deep shade (though I have some in a very dark area) and they do not want to be too deeply planted. Scrape away the soil from round them exposing the top of the corm and see what happens.
We have both as lawn weeds and they do not seem to mind either the competition from the grass, nor the mowing.