I don't have any Callas, they won't grow here. But my understanding is that they are deciduous and go dormant for the winter. That's probably what's happened to yours.

they need a dormant period like caladiums 2-3 months. so you can keep them in pots for a couple of months dry (in the garage), then lift, brush off old soil gently and repot into new mix. water lightly and no more until you see new leaves emerging, then you can water again lightly. once a couple of leaves are good - you can start watering normally.
i have difficulty blooming mine too (not enough sun i think). but it's pretty normal if they don't bloom 1st year. perhaps, you'll need to give them more light? like dappled shade? depending on the season of course.
normally the white ones should bloom about 2 mo after leaves emerge, for colored ones it could be up to 3mo.

Your plant probably bloomed before you got it, they usually are sent to chain stores already in bloom. Petrushka gave you some good advice about dormancy.