You could try a different yeast (run the must through some muslin to remove the yeast that is in it and make up a new batch of yeast starter with a different yeast brand – try baker’s or brewer’s yeast if you are using a wine yeast now)

Try to reactivate the must by giving it a really good shake and putting it somewhere warmer (above the fridge, next to the water heater) If this works, wrap the container in a blanket to keep the temperature even.

Cranberries are a very bitter fruit and the amount of sugar in the recipe may have been too low to sustain the yeast beyond the short fomentation you describe. You can add sugar water to the must, but the resulting taste will probably be a lot less cranberry and a lot more bland than you would hope for.

Also check that your air lock is complete – if you have a leak, there may be fermentation going on that you are missing.