Papumba has prizes that are unlocked as some learning activities are completed, these prizes come in the form of "collectibles".
There are also different 'levels' of collectibles, some are normal and others are silver or gold. Each color represents a different collectible.
It´s important to remember that the collectibles are saved on your device, which means that if you have 15 collectibles on your phone and tomorrow you uninstall the app and reinstall it, these will be lost.
Knowing these, If for some reason your kid can no longer find their collectibles, one of these things could be happening:
1) If you have an Android device, maybe to get more storage space you cleared the cache of the app, and therefore deleted the earned collectibles.
2) You changed your device or reinstall the app, so your child's progress was deleted.